We want to minimise the risk of breaking working code. Making it easy to adjust this recursion limit separately from the main recursion limit by using a scaling factor is a good way to do that. It shouldn't increase the maintenance burden in any significant way, since the ratio of the stack depth increase in the compiler vs the main interpreter loop should be relatively constant across platforms.

Autogenerated code could easily hit the 1000 term limit - if anything, I'd be inclined to set it *higher* than 4 rather than lower, as breaking previously working code in a maintenance release is a bad thing, regardless of our opinion of the sanity of that code.