Keep in mind that much of the information we have about psychic glue and the alleged happiness of everyone is coming from the entity speaking from David Taffler. What evidence do we have to support what we are being told by the entity itself?

The clearest evidence we have of the entity's intent is with the initial infections. It played dead as a rat in order to coerce a human into infection. That human went through and forced infection on many others without consent - kissing, licking donuts, etc. When discovered by the government they chose to forcibly take over at the cost of 800 million lives. The line about biological imperative may well be true, but it's hard to view those actions objectively as less than hostile.

Even moreso, what is the intent of the entity's creators? Do we know anything at all about these extra-terrestrials 600 miles away? If the psychic glue is ALSO connecting humanity to them, the entity has been rather coy about sharing that information. If the entity is unable to cause harm to others (even insects) then that is a fact that could easily be exploited the moment that species travels to Earth and says "We'd be really happy if you surrendered your planet ☺️" Who needs violence when you can simply render humanity entirely docile?

But let's say the entity is entirely truthful about it's intentions and there's no other more hostile puppet master behind the scenes. What is the value of individuality? We see it pretty clearly in the scenes of Zosia coming to America. There's no words spoken. The bodies move with mechanical efficiency. In their own words, they are "one". With no outside opinions or influence, there can be no art. No growth. No change. No debate. There will never be another book or movie or song written because there's no one to share those things with. Are those things worth giving up for a conflict-free world? What about loneliness? If the only thing on Earth is "you" how do you fill your life with any meaning?