No. The default value should be 'off', unless it's _needed_ by people.
Have you guys looked at the size of the kernel lately?
Bloat is bloat. Just because it's conditional is not an excuse.
Having an in-kernel memory tester is in no way better than having an out-of-kernel one that you pick at grub boot time, so the claim that it's a "recommended" thing is likely bogus too.