Can you elaborate why you think Touchwiz is so terrible and why it's such a huge deal to you?
Sure. I can answer that one as a guy who loves Samsung hardware but hates Touchwiz:
1. Touchwiz has this "Fisher Price" feel to it. With the bright colors and big tap targets it makes every Samsung feel like a combination of "baby's first smartphone" and "The Jitterbug Smartphone." It basically assumes you are an idiot (which I guess is why Samsung dominates Android). "You don't have to break out the glasses gramps, everything is HUGE." One of the first thing people want to do with a hacked Samsung is change the DPI for a reason.
2. Thanks to Touchwiz it takes longer for flagship Android phones to get updates, as they have to get it from Google first and THEN ruin it by adding Touchwiz. Samsung has a great and deserved reputation for supporting old phones with new Android, but the fact is that takes them a while to get those updates to devices and some that are still "supported" don't get a new Android update until that update is almost replaced by Google.
3. When you get new Android updates, thanks to Touchwiz the big features of that update are almost all gone. All the cool features you read the next Android version was going to have are almost all ripped out and replaced by a Touchwiz "solution" that is exactly the same as what your phone had before. They do this because normals hate change, but the practical effect is unless you ROM your phone you can get every Android update and still feel like you have a two year old device. Basically the Android updates just become an app compatibility thing, and not an "oh goody what did Santa Google stick in our Android stocking this year?"
4. Touchwiz slows down the phones and eats more battery life. Period. The Google Play S4 got MUCH better battery life than the regular S4, and EVERY Samsung phone feels more sluggish than it should. Touchwiz is to blame. Also Touchwiz eats a ton of storage space. On my S4 I had like 5 gigs free on day 1 thanks to Touchwiz. They have gotten better with this, but its not near stock Android or even a Moto.
5. Touchwiz pushes you to Samsung's garbage solution. So instead of Google Now you get S-Voice. Instead of the Google Calendar it pushes you to Samsung's calendar. It has been obvious for years that Samsung is trying to make their devices unique, but they have gone too far. Maybe the idea was to make it so they could switch out Android for something they controlled more one day (like Badu) and no one would notice because the apps are the same, but the practical results are that Samsung devices don't leverage the power of Google like a Moto or a Nexus does.
Is 5 reasons enough?