Yep, As you say times have changed, I just do not understand why, If you have already stamped out of Thailand then why can you not use a different valid passport to stamp into another country ??
I am not talking about a visa run, I have never actually done one of those. I flew into Thailand and then exited through the border crossing into Malaysia on my way to Singapore. The reason I used both my passports was due to work visa's I had for malaysia at the time, were in a different passport than my Thai visa.