Everything in the game has to work together to as a full final package. If I kept all the old stuff the same, it wouldn't work well with the new stuff. It may feel strange at first when things change during development, but could you imagine how strange it would be, especially to a brand new player, if the character designs, art style, and vocal style of the whole game suddenly changed after the first few stages while playing the final game itself? I'm glad you had so much fun with the test demo, but I never really intended for people to get so attached to it, hence why I've always been clear to say everything's "Subject to change in final".
Feeling less connected to something because you aren't as used to it is a textbook case of nostalgia. You have memories and feelings associated with the version you played that you naturally wouldn't have with one you're not as familiar with, and that's okay. No matter how good something is, the "special flavor" is something you have to find in it with new memories and experiences.
If you want to recapture that old feeling, the old demo's still playable, but if I wanna make the game I truly want to, I have to be able to move forward. Either way though, thanks for your support! :)