Isn't it kind of the goal to assimilate? What's wrong with assimilatists?

I'm not a very online person, so this was a new word for me to be honest.

As a trans person it's my goal to pass as cis as possible and live a normal life in our society. I probably won't be able to go deep stealth since I want to help other trans people in the future, but I want to pass as cis, be seen as any normal man.

I also think the goal of transitioning should be passing as cis, simply from a logical stand point. I accept people who don't want to pass as cis, but I really don't get it.

I also think we should bridge the gap to our cis brothers and sisters, since we've got more in common than what makes us stand apart. We're really just normal people in a mismatched meat suit and I stand by that. There isn't any reason cis people shouldn't accept us, that isn't simple ignorance or repressed gender insecurity. There are many cis people that have doubts about small topics, who aren't transphobic in my opinion. They might be against for example trans people in sports, children transitioning but accept trans people as whole. (I generally share some concerns about that)

From my standpoint that's just common sense, so help me try and understand what's the issue with that.