On raw performance might, the M4 really does live up to Apple’s promises, should deliver. Single core is up about 20% compared to all M3 chips and more than 40% compared to M2. The generational computational leap from the previous M2 iPad Pro is at least a 42% jump on single-core and multi-core.
Market segregation is worth it for them and the chips will be used in plenty of other hardware anyway, so dumping them in iPads doesn’t hurt, even if it’s mostly just marketing fit the products, nor does it necessitate a product change.