Alright, I'll play... I'm a retro grouch though, so there's lots of tech that's been made that I do not care for...
Indexed shifting - I've been tasting the koolaid lately on my Miyata 1000, but it came with that and it's my nicesest bike (also @ 1990 my most modern) so I wouldn't say I'm any sort of convert. I grew up with coaster brakes (didn't we all?) and lusted after freewheels and drop bars that I used to see go by daily on the country roads. I've been friction shifting since the '80s and have absolutely no problem with it. Seriously, how hard is it to listen to your chain and determine if you're in gear or need to trim a little? If the SIS died for some reason on the one bike that has it, I'd not put any effort into replacing it with another indexer, I'd just put frictions on it and move on. The fuss of getting the indexing tuned is just a PITA to me and time I'd rather spend doing something like riding.
Fixed wheel - not going to happen, with a few exceptions I despise what is generally done to these bikes in the vein of being "cool". I don't care for cool, and I *really* like coasting down hills. If I have drops and a freewheel, I'm happy - I like to get low and feel like I'm flying down hills. Can't do that on a fixie with straight bars, and my double-surgery knee would never forgive me either. I am open to the idea of a single speed however, as long as it has low bars and can coast.
Carbon fiber - I don't get it. My friend has a $5,000 cf racing bike and it weighs only a few pounds less than my chromoly bikes. I may be hauling a few more pounds, but it won't shatter on impact. Maybe it's my experience with vintage Simplex, but plastic in any form has no place in key points on the bike. Just my opinion. I heard a cf bike ride by the other day and I even disliked the *sound* of the stiff frame. Seems like a solution looking for a problem in my mind.
If light and expensive is your taste, go titanium. If my bike had carbon fiber I'd spend the whole ride being afraid of the darned bike and that's no fun.
Aluminum - while I'm complaining about stiff frame materials, I'd gladly take aluminum over plastic, but I've seen aluminum straight out crack on a mild impact, and I don't find aluminum bikes are really any lighter than good steel, just chunkier. Seems to me like frame makers are pulling a fast one on consumers with this material. Some how jumbo tubing is a selling point, but I can't fathom why. Alloy is fine on the components, even if they break it's replaceable but a cracked frame requires a whole new bike.
Belt/shaft drives - again, a solution looking for a problem. Are chains really a problem?
More than 10 speeds - frankly 10 is probably more than I need. I probably use a third of the actual combinations at best. I do like the bikes from the '70s that came with them though, so I stick with 10 gears. I've tasted the 12 and 21 combos and find it has no advantage that works for me enough to swallow the koolaid.
26" wheels of the modern variety - small, wide tires. Blech. Need I say more? I am considering fixing up a set of 650A for my new (1979) beater so I can get some traction and fenders for winter this coming season. Sort of 26" but not as fat.
Same goes for 29'ers, I don't see me slapping fat tires on a 700C wheel anytime soon. I tried to re-live my MTB days for a while, but the koolaid didn't take.
Since SIS is a weenie device in my mind, electronic shifting is naturally right out.
Campy - sorry, some may not agree, but the nicest C&V campy RDR looks like no match for a Cyclone. Plus all of my bikes are Japanese/ Japanese-Canadian/ Japanese-British, so there's no room for Italian bits in my stable. I do like the look of some Campy cranks and seat posts, but I'm not gonna spend money on them.
I did drink the Tektro aero lever koolaid, however.
Basically if it came out after 1980 or so, my interest dwindles significantly.