I find there are are generally two schools of thought when this comes up:
1. Don't teach VFR pilots how to fly on instruments because it will lead to a false sense of security and cause them to push on in worse weather than they otherwise would, or
2. Give everyone some basic instrument training so if they happen to be in an aircraft that at least has an AI or AH of some kind, they might have a fighting chance of maintaining control when visual reference is lost.
I believe 2 is best, and am very thankful for my instrument training, the more so because it was old school and covered limited panel (i.e. no attitude instrument) UA recoveries. Make it compulsory, I reckon, particularly as noted above by machtuk that many more modern machines, or old ones with a TV screen added, have a decent AI and compass built in.
And don't only teach how to maintain control on instruments, and climb and turn, but hammer home some scenarios about how to avoid losing visual reference in the first place, but if you do, extending the thought process into 'now how am I going to safely get visual again'.