The people opposed to the “Bein Hazmanim” season/s for bachurim and kolel yungeleit are usually the most unhappy individuals. They have accomplished nothing in life and have nothing to look forward to. The fact that the Shul is more crowded in those times annoys them. They need to change their attitude. And their outlook on life.
The Bein Hazmanim furloughs started in the times of Gemara. Where one of the Roshei Yeshiva told his talmidim ..”I don’t want to see any of you (in Yeshiva) in the month of Nissan and in the month of Tishrei. Because the economy was agriculturally based in those days. Most people owned or worked on farms and the extra hands were needed for the harvest.
In later years when most famous yeshivas were located in Eastern Europe, sometimes in small towns, it took a long time for the students to arrive back home for Pesach and Rosh ha-Shana. So let’s not begrudge (fargin) the yeshiva/kollel their well deserved vacation.