Clearly there are a number of mechanics that need to be worked out, however
it certainly cannot adequately be described as matter of symmetry. While SoaSE is an RTS, it
is more importantly a 4X. As such game length and greater number of base game elements (unit roles, buildings, research...etc) is a major detractor both in popularity in the community. This makes as you describe am accurate
and fair rating systems more difficult where a DoTA match could last 20-40 min or SC match rarely going more than 2 hrs
Obviously this isn't all but my main point is every game has its own personality, knowing your preferences can help from ruining your expectations.
Also I'm a long time chess player, and there is an enormous gap between Chess (if you want to call it a TBS) and SC or SoaSE and not just because they are RTS. BTW Fischer realized randomness was a necessary element needed to continue competitive chess and that is how chess960 came out. If perhaps Deep Blue had faced Kasparov progressively in chess960, Kasparov would have been kicking it's ass to this day since the book of openings would be much larger.
I think personally that as human computer interfaces evolve the 4X gaming community will grow as the macro-management heavy SoaSE can be more seemlessly integrated with RTS like SC where quick micro is valued. In the meanwhile there is important research still being done in RTS AI and design.