RX7 makes 261 NM which is hardly torqueless. Less than what most cars get, but not gutless.
Tuned rotaries do get bad mileage, but so will a tuned piston engine with a rich AFR. People like to think that just because LS engines get good mileage piston engines automatically get better mpg but the FD RX7 posts slightly better MPG values than a Lancer Evolution X. Granted it's on 20 year old data, and owners report like 12-16 at most on city, but it's still not much less. Older JDM spec Evos are said to get less than 10 mpg city.
Also rotaries are only unreliable in a daily driver sense, and yes 100K mile rebuilds are unacceptable no matter how you look at it. But in racing/tuned applications how many engines can realistically last 100K under high boost and heat? Rotaries don't get "internal" mods aside from maybe seals, but even then most people use OEM seals until they start making north of 500 WHP. Prepping a piston engine for high power and boost can be costly, with all the balancing and porting and new internals needed.
The LS is special because it is that good (And even then they have their fair share of problems). Even engines like a 4G or 2J or RB will not be cheap to make power out of, despite what JDM bois will tell you.