Yeah I hear that about a lot of Mud Terrain tires as far as wet conditions go. Most block style MTs don't do good in wet conditions, it's the ATs and car tires with more rubber touching the road and the siping that helps.
For the record, Goodyear still makes the old style MT/R, but it is sold exclusively to the US military in 37/12.50/16.5 only. You can get them anywhere from brand new to bald thru gov surplus/liquidation. Same with the BFG Baja T/A's.