IMO, residual forward thrust is more important a factor in wet/icy runway conditions than the availability of any significant amount of reverse thrust. I have been in one situation where idle reverse was the only thing that kept me from going off the end of the runway in a 747, and I know of at least 1 other case in our airline where the non-use of reverse caused an overrun at low speed.
Bigger engines with bigger fans have significant idle thrust, and with poor braking action it may well overcome the ability of the brakes to slow the airplane below taxi speed. At least the A380 negates the thrust of about 2.5 engines with 2 in idle reverse...