Re: Scylla and Carybdis
"I've never come across anything - in 15 years of using Windows professionally - that absolutely had to run as a full administrator, usually it's a single registry key, file, or the like."
When I was in the market for children's (under-10s) games a few years ago, I found that just about every one insisted on Admin rights either because it needed to tonk all over my display settings or because it needed to hand-grease my CD-ROM's spindle to support some amazingly clever "anti-backup" mechanism.
I dare say that a few weeks spent playing with shims, registry keys, Process Explorer and the like would have yielded solutions in most cases. I'm prepared to bet that most of the general public just granted admin rights to their toddler's account and bought the software again when the disc got scratched beyond recovery.
Designing apps to avoid admin access SHOULD have been part of the Windows landscape for the last 20 years. (The security model dates from about '92.) Microsoft were still shipping violations about 10 years ago. The games market may be OK now (haven't looked) but certainly wasn't 10 years ago. If you've been fine for 15 years, you've been working in a fairly restricted portion of the marketplace.
"and really people relying upon this kind of legacy software should totally understand their software by now and know how to install it properly."
Is this the general public we're talking about? The same people whose existence made Microsoft hesitate for so many years to remove AutoRun?