This sounds like a uniquely you problem. I've never known anyone go to IKEA buy a wardrobe, cart it home, and then not build it. Even the wife who is an infamous collector of rubbish and probably the world's best procrastinator has all her IKEA purchases built within a weekend. Some of your points make sense, but some are truly bewildering:
1. Yeah number of parts can sometimes be a shock.
2. I've never known anyone to "take inventory" of anything from IKEA. They open the box when they want to build and build it. It's virtually impossible to actually properly take inventory without actually making a whole mess of a room in order to build anything sizable anyway - furniture isn't small.
3. YES. Oh god yes, there are quite a few examples of this. It's like one of those spot the difference puzzles rather than an instruction manual.
4. This is a bit more of a strange one, I don't expect someone who hasn't got a screwdriver and hammer to actually buy anything flatpack. Also any tool that isn't a screwdriver or hammer is included. IKEA famously requires very few tools.
5. I don't think the memory of something taking time to build lingers anywhere near as much as the satisfaction of having it completed. In fact the only people who probably do have negative memories of the build time are those who built it wrong, bought it wrong, or built it in the wrong room and realise they need to unbuild a portion of it.
6. Yes.