I was just wondering why women aren't allowed to give sermonettes and sermons?

I think that women could give equally inspiring messages. Although we can give our ministers ideas for sermons, it might have more impact coming from a woman's perspective.

In many Christian denominations, women preach and are ordained as ministers and pastors. And some of them are quite dynamic and articulate! However, since we get our guidance on such matters from the ScripturesThe divinely inspired writings of both the Old and New Testaments. The term Scripture is used in the New Testament to refer to both the Hebrew Bible (Luke 24:44-45) and the new apostolic writings accepted as inspired (2 Peter 3:16; 1 Timothy 5:18)., it is to the BibleThe books (Greek, "biblia" ) that are acknowledged as canonical (authoritative) by the early Christian Church. It includes both the books of the ancient Hebrew prophets and those of the apostolic witnesses to Jesus Christ. that we look for direction on this subject.

Examining the ScripturesThe divinely inspired writings of both the Old and New Testaments. The term Scripture is used in the New Testament to refer to both the Hebrew Bible (Luke 24:44-45) and the new apostolic writings accepted as inspired (2 Peter 3:16; 1 Timothy 5:18)., we do find that women held many very important roles in the history of Israel and the Church. Women such as Ruth, Esther and Deborah were important in both leadership and serving within the plan of God. In the New TestamentThe 27 authoritative books of the apostolic writings: the four Gospels of Christ, Acts (a history), 21 apostolic letters and the book of Revelation., we find that the older, experienced women (wives and mothers) were to teach the younger women.

Titus 2:3-5 [3] The aged women likewise, that they be in behaviour as becometh holiness, not false accusers, not given to much wine, teachers of good things;
[4] That they may teach the young women to be sober, to love their husbands, to love their children,
[5] To be discreet, chaste, keepers at home, good, obedient to their own husbands, that the word of God be not blasphemed.

See All... says, "The older women likewise, that they be reverent in behavior, not slanderers, not given to much wine, teachers of good things—that they may admonish the young women to love their husbands, to love their children, to be discreet, chaste, homemakers, good, obedient to their own husbands, that the word of God may not be blasphemed."

We also find that many early Christian women taught their families out of the Word of GodThe books (Greek, "biblia" ) that are acknowledged as canonical (authoritative) by the early Christian Church. It includes both the books of the ancient Hebrew prophets and those of the apostolic witnesses to Jesus Christ.. Paul reminded Timothy of the things he had learned as a boy from his mother and grandmother. In 2 Timothy 1:5When I call to remembrance the unfeigned faith that is in thee, which dwelt first in thy grandmother Lois, and thy mother Eunice; and I am persuaded that in thee also.
See All..., Paul wrote, "When I call to remembrance the genuine faith that is in you, which dwelt first in your grandmother Lois and your mother Eunice, and I am persuaded is in you also."

Clearly, Paul was referring to the fact that much of Timothy's faith and understanding came as a result of the example and teaching of his mother and grandmother! Obviously, they were very good teachers. Notice later, in 2 Timothy 3:14-15 [14] But continue thou in the things which thou hast learned and hast been assured of, knowing of whom thou hast learned them;
[15] And that from a child thou hast known the holy scriptures, which are able to make thee wise unto salvation through faith which is in Christ Jesus.

See All..., that Paul refers to the teaching Timothy received when he was a young boy: "But you must continue in the things which you have learned and have been assured of, knowing from whom you have learned them, and that from childhood you have known the Holy ScripturesThe divinely inspired writings of both the Old and New Testaments. The term Scripture is used in the New Testament to refer to both the Hebrew Bible (Luke 24:44-45) and the new apostolic writings accepted as inspired (2 Peter 3:16; 1 Timothy 5:18)., which are able to make you wise for salvation through faith which is in Christ Jesus."

All of that said, when it comes to teaching in a Sabbath service, God gave that responsibility to the ordained elders of the Church—which were men. In 1 Timothy 3:1-2 [1] This is a true saying, If a man desire the office of a bishop, he desireth a good work.
[2] A bishop then must be blameless, the husband of one wife, vigilant, sober, of good behaviour, given to hospitality, apt to teach;

See All... it says, "This is a faithful saying: If a man desires the position of a bishop, he desires a good work. A bishop then must be blameless, the husband of one wife, temperate, sober-minded, of good behavior, hospitable, able to teach."

Throughout the New TestamentThe 27 authoritative books of the apostolic writings: the four Gospels of Christ, Acts (a history), 21 apostolic letters and the book of Revelation., the ordained elders were to be the primary teachers during a Sabbath or worship service setting. Paul even wrote that women were not to be fulfilling that role within the Church: "Let your women keep silent in the churches, for they are not permitted to speak; but they are to be submissive, as the law also says. And if they want to learn something, let them ask their own husbands at home; for it is shameful for women to speak in church" (1 Corinthians 14:34-35 [34] Let your women keep silence in the churches: for it is not permitted unto them to speak; but they are commanded to be under obedience, as also saith the law.
[35] And if they will learn any thing, let them ask their husbands at home: for it is a shame for women to speak in the church.

See All...).

In his letter to Timothy, Paul added, "but, which is proper for women professing godliness, with good works. Let a woman learn in silence with all submission. And I do not permit a woman to teach or to have authority over a man, but to be in silence" (1 Timothy 2:10-12 [10] But (which becometh women professing godliness) with good works.
[11] Let the woman learn in silence with all subjection.
[12] But I suffer not a woman to teach, nor to usurp authority over the man, but to be in silence.

See All...).

These verses may seem to be a bit harsh or direct today; however, Paul was dealing with a number of issues that were resulting in people not serving or functioning in their respective roles—and there was confusion on this issue. These teachings are not a matter of ability or importance of women—but the teaching role that God defined in the BibleThe books (Greek, "biblia" ) that are acknowledged as canonical (authoritative) by the early Christian Church. It includes both the books of the ancient Hebrew prophets and those of the apostolic witnesses to Jesus Christ..