Is it really necessary to look for Earth-like habitable zone planets, when it is likely that the "humans" to reach that planet will be bio-engineered or entirely mechanical by the time we would be exploring "in person?"
The possibility of exploring exoplanets is so remote it is not a factor. We are interested in Earth-like planets as there is only one type of planet that we know can support life, and that is the Earth-like ones.
We are interested in Earth-like planets as they may provide a habitat for alien life. The question of "does extra-terrestial life exist" is of intrinsic interest.
I recently joined a project on exoplanet habitability, and have worked with other physics research in the past. An underlying issue considered by people working in these areas is "does it really matter?" It's a good question, and hard question to answer even for scientists.
You can expand your question to whether astronomy itself is worth studying. I would argue it is (one reason I joined the project).
Exoplanets were discovered relatively recently, making interest in them sky rocket. Just like how astronomers study stars to find how our sun was formed and how it will live out its life, exoplanet research can reveal how our solar system was formed as well as how it might evolve in the future.
In addition to the search for life, simply by observing other systems with different sizes, and in different stages of their formation and evolution, we can better understand our own as well.
As an aside, research for the sake of knowledge is fun! :) But of course it sometimes leads to unexpected yet important discoveries.
Your question comes across as more of a complaint than a true question. Whenever you ask, "Is it really necessary..." it is easy for someone to respond, "Is anything really necessary?" If people are interested in searching for other planets that may be habitable, why not just see what they find? Most people would find it fascinating/interesting if we verified a "second Earth" were truly out there.
You then make a wild assertion using "humans" in scare quotes, assuming that we'd be mechanical or entirely separate entities and therefore only non-human entities. Would you feel the same way if such a planet were less than 5 light years away? 10? 15?
I would suggest that if in the next 100 years we have enough research to show that humans could walk around and breathe on a planet less than 10 light years away, that there won't be anything anyone can do to stop humans from beginning the development phase of ambitious projects to reach that world.