What is a bootleg cut? Here it means a broad flare at the bottom of jeans to accommodate western boots. Regardless of the definition, I strongly recommend ignoring all trends in suits. I order my suits today much the same way I did a dozen years ago and am therefore happy with any suit I pull out of the closet. Suits were done evolving in the 30s and 40s. I strongly recommend you hunt for some of the Esquire or Apparal Arts illustrations, which ran through the 50s, and you will see what I mean. There is very little from that series that I wouldn't wear today, and I don't pretend to dress in period clothes.
The baggier pant leg is certainly a return to an earlier era, although trouser widths certainly varied over time. As far as I can tell, the higher waist simply makes sense if you want your trousers to sit at the waist rather than the hips. Suspenders simply work better, although a well cut pair of high-waisted pants will sit well by themselves - certainly Fred Astaire was famous for doing without the braces, although I doubt he would have been able to get away with just a scarf to hold his pants up if he were buying off the rack.
