Observance of commandments that supposedly oppress life

It makes no philosophical sense for God to want something that is not good for a person, and if they claim that He wants it, it seems problematic to me to assume that it is indeed true on this basis. The book "Education" was written, for example:
Fasts are not only mourning, but also Yom Kippur, for example.
You can also mourn for things that are not oppressive, such as other prohibitions.
During a hard fast, spiritual forces are sometimes oppressed, and this prevents me from praying well, for example on Yom Kippur.

In other words, you expect the halacha to require dancing folk dances on Tisha B'Av, going to the beach on Shabbat, and doing penance every day at a party of mischief, and the rest of the time, when there is a break from the sex parties, we can speak slander for our own pleasure. What a mistake! How did he not think of that?

You went too far.. maybe to refine your answer but still..
The question is not about a hedonistic and overly materialistic person but about a spiritual person who is connected to her ‘ and the Torah

Why necessarily oppressive? There are people for whom restrictions and prohibitions actually bring them a certain pleasure. Otherwise, there would be no people who asceticize and accept strict rules upon themselves.
In fact, several of the most important philosophical schools in the ancient world imposed strict rules and asceticism on their members, sects and religions everywhere in the world established monasteries and nunneries. There are people for whom sadness makes them enjoy themselves, and there are those for whom the restrictions remind them that they have a purpose or give them the feeling that they transcend their temporary body and their human urges and needs that remind them of death.

Moreover, those mourning customs began as a spontaneous expression of the people who mourned the destruction. The Jews only codified the matter so that on the one hand the destruction would not be forgotten in the future and to prevent negative phenomena that spontaneous mourning can bring. Just look at the Shiites on the day of the tenth day how they beat themselves.

If there is anything that does not make sense, it is the lamentations over the destruction. People these days read laments about ruined Jerusalem and then go out into its busy streets. Here it really doesn't make sense and even seems quite bizarre.

The Temple has not yet been built and we are not in a state of complete redemption..

It is important to clarify that all the commandments are good, uplifting, and joyful, as the Torah commands joy - which sanctified us with its commandments..
The discussion is about certain things only