I am confused, warrior is the best melee DPS spec after UDK/FDK in raids. The 2nd best after Enh shaman in M+.
The problem is never in comparison to melee, it is that warrior in m+ is not comparable to ranged DPS who - take less damage, is always safer due to being ranged and they bring more of everything. This season bringing melee is not worth the drawbacks of doing so.
In raids warrior is just a fine mid of the pack spec. Not bad, not excellent. Just a solid pick as the warrior will be the last one to die during progress and got a solid DPS profile to finish the fights.