I'd like to try and answer or rather mount an argument against the specific question "why do rotaries suck".
Before I start, I have a diploma and a degree in Mechanical Engineering, however, my argument has nothing to do with thermo dynamics, swept volume, number of rotations or any other techno terms and phrases that this discussion has raised. In fact, when I fell in "love" with rotaries, I had little understanding of how they actually worked.
Let me take you back to 1988, I was 16 years old and was driving a weber fed 13B RX4 coupe (yeah, okay I'm an old bugger!). These were the days before rotary hysteria had taken place, and in fact, the "rotor heads" were the minority and rotaries were hated and totally disregarded by everyone. If you wanted to go fast you were typically driving a Ford, Holden or Chrysler with a V8 or stinking hot six. Rotaries were given absolutely no respect. Terms like chook cooker, rotisserie, wanker engine, rice burner, jap crap and various other names were hurled as abuse whether you cruised through a carpark loaded with other car enthusiasts, or pulled up to a set of lights on Saturday night.
The reality for me was, the more people stirred me up, the greater the pleasure was to blow them away at a set of lights. I never forget the night when a 360 Chrysler pulled up next to me and the the passenger was making chicken noises and flapping his arms like a chicken, the driver was also laughing in hysterics. Lights turn green, a screech of wheels, 1st, 2nd, and 3rd gear to 8000rpm and the Chrysler is in my rear view mirror. The next set of lights the Chrysler pulls up again. This time there is no laughing, and both guys are looking straight ahead, pretending I'm not there. This scene is is repeated multiple times on any given night. Unfortunately, although the little rota proves itself time and time again, the competition decides not to acknowledge the performance, or acknowledges the defeat by hurling further abuse.
Fast foward to 1998. I'm still with an RX4, but now it has a turbo. I'm at a dyno shoot out, and my quiet, smooth idling RX4 just pulls an impressive 270 something RWKW. I'm beaten by 2 or 3kw by a guy in an AC Cobra replica with a 429 big block, Motec injected blah blah blah. The rumor was he had spent 40K on the motor. It was an impressive motor and vehicle without a doubt. After the event the owner comes over to me, and with his strong european accent, asks to have a look at my engine. When I pop the hood his eyes almost pop out of his head. His comment was "wholly f**k, where is the rest of it?. That thing makes all that power?".
Okay, I've rambled on here. But unless you've owned a rotary, you probably can't appreciate what I'm saying. Forget about whether it 1.3,2.6. or 3.9 litres, and whether it's 2, 4 or any other stroke of an engine. These are great little engines that for many many years have been given very little respect by the majority of car enthusiasts, even though their performance was widely proven. Matched with the right car, they are damn hard to beat on the street or the track. They are a performance engine and as such need to be treated accordingly. Flog the arse out of them day in and day out, they won't last (what engine would?), look after them and they will give a reasonable life.
In short, rotaries don't suck - I guess it's just down to personal preference. The history and heritage of the rotary is such that most guys that enjoy them are probably more sensitive to criticism than most.
My two cents. Good thread, let's not make this personal.