I think the biggest issue is the lack of arithmetic with overflow checking, especially with a variant that calls a location in a control register on overflow.
This makes it very inefficient to compile languages that would like overflow checks on all arithmetic.
A comment elsewhere here pointed out that RISC-V can do it with two fused compressed instructions for the most common operations. So seems like they did the right trade off to me.
This makes it very inefficient to compile languages that would like overflow checks on all arithmetic.