Because one is not supposed to make a blessing which is not required, the poskim generally frown upon innovating new blessings that were not practiced by previous generations, especially when the proposal to say the blessing is based on conjecture and not clear proof.
Rambam in Moreh Nevuchim part 3 chapter 14 admits that not everything that the Sages knew about astronomy was correct and unfortunately Rambam's astronomy also was wrong because he relied on the astronomy of the ancient Greeks.
See also Pesachim 94b, where Rebbe admits it is possible, that the non Jewish scholars had on some issues of astronomy, a better understanding than the astronomy used by the Jews.
See also Rabbi Avraham the son of Rambam's introduction to the Agadot, brought at the beginning of Ein Yaakov, where to summarize his views, he understood, that if the non Jews bring weak scientific proof for their views (on scientific issues) we just say it appears that they are correct. But we will only say that the halacha (Jewish Law) follows their view if they bring very strong scientific proof.
In light of this, it is not so simple to bring proofs from the scientific reality that we see today, to prove what was in the mind of the Sages, when they instituted the recital of blessings over certain astronomical events.
Because one is not supposed to make a blessing which is not required, the poskim generally frown upon innovating new blessings that were not practiced by previous generations,
Because one is not supposed to make a blessing which is not required, the poskim generally frown upon innovating new blessings that were not practiced by previous generations, especially when the proposal to say the blessing is based on conjecture and not clear proof.
In the article at
http://machonshilo.org/en/images/stories/files/Birkath-Hama-Response-02.pdf
that Tag-MehirTzedek
and Kahane-Was-Right BT
are referring to, Rabbi Bar-Hayim Shlitta in the first few points of the article offers a conjecture, that Rashi and Rambam mistakenly accepted a reading of the Gemara which portrays Abaye as supporting saying Bircat Hachama once every 28 years.
Although what Rabbi Bar-Hayim Shlitta, contended might be right, he might also be wrong.
It's too risky in my opinion to change custom based on conjecture.
In addition, if I did enough research, I could "dig up" a lot of blessings that some important Rabbi in the past thought we should say, but it is not the accepted custom. So even if the great Rabenu Bahye (I'm using the spelling of the article) did support saying a blessing at the solstice, this is not enough in my opinion to break with the accepted custom.
http://www.pardes.org.il/online_learning/weekly-talmud/2009-08-06.php
How often can this blessing be recited? If someone lives with a beautiful person, should they recite the blessing daily? Monthly? Yearly? According to one prevalent opinion the blessing can be said only once over a particular item. Once the benediction has been pronounced over a certain beautiful person, for instance, it cannot be recited again - ever - over that same person (Shulhan Aruch). Others maintain that the blessing may be recited once every 30 days (Meiri).
Alas, this blessing has largely fallen into disuse, and is at most recited without the Almighty's name. Why do we not say this blessing nowadays? One codifier in the early 19th century suggested that in our modern reality we are exposed to a whole gamut of images, and hence we have become desensitized to wonderful scenes, pictures and spectacles that a blessing is no longer warranted (Rabbi Avraham Danzig, 18th-19th centuries, Vilna). If this could be said about the early 19th century, it is all the more true in our day and age when technology has brought untold vistas into our homes.
Every 28 years the sun returns to the same position, at the same time of the week, that it occupied at the time of its creation—at the beginning of the fourth day of creation. A special blessing – called Birkat Hachamah, "the sun blessing" – is recited to mark this event. Due to the rarity of this event, this blessing is customarily recited amid large public gatherings of men, women and children.
I don't believe Rabenu Bahye invented the bracha, and you also know that is not the case, yet it seems as if your comment is giving that impression.
The summer solstice happens every year, thus it is not an occasion like Birchat HaChama which happens every 28 years. I said Birkat Hachama last time we had the opportunity to say it {was it about 2 years ago?}.