I agree non-removable battery isnt a big issue to me long as your software is solid and doesnt freeze. but how can you know the one wont stand up to the s4? their specs are nearly identical with the one having the (debatable) better screen. camera wise the s4 may be better as far as taking pictures but i honestly couldnt fathom the s4 having better features camera or sound-wise. design and screen size will be subjective. apps will match. its gonna come down to touchwiz vs sense 5, 4.7" vs 5" screen, and battery.
Because HTC goofed before. That's why Sprint started selling the HTC One X (EVO 4G LTE) for $100 less than the S3 because of all the reception issues and the fact it didn't get 4.1 till after the S3. Hell they even stopped showing the commercials for it and it was supposed to be Sprint's "flagship" device.
I ain't sayin HTC can't come back, but in the eyes of a somewhat educated consumer they're not somebody who you really want to put your money and faith in that they'll make a quality device based on their recent track record.
That's just my outlook on it though, I'm sure there's a lot of ppl who agree and disagree.