It's not competitive because
1. The maps are not designed in a competitive way.
2. Core game mechanics (map control, positioning, well mixed army force) play less of an role
3. There are not enough "competitive/ good players".
When I played those modes extensively for a 6 month period (stopped about 1-2 months ago) there were hardly any players I'd call good. I consider myself a mediocre 1vs1 / 2vs2 players, yet me and my team were kings in those modes. Holding #1 for axis & allies because most games were over before 15 minutes, I can only recall about 3 deserved losses (all other loses were due drop hack or bugsplat) and those were also only against those teams that hold 1-3 position. Even those players that were top 20 ( I had always elo running) were just bad and checking their playercards often revealed ranks 500+ in 1vs1 & 2vs2.
Again it's not about ranks, its rather about understand and excelling in core game mechanics, those mechanics which are necessary to master when understanding balance.
Your 3 points u mentioned:
1. Maps are designed in competitive way or not? similar to other mode's maps some of them are some of them are not, so no difference. there are actually some maps which are designed very well, some maps which favor allies more, and some axis', some are balanced some not. exactly like other modes.
2. According to what? If you wanna play at competitive level you gotta actually take em all into account. You can have your own/team strategy, but again there are big differences between those mods in the skills u require; map awareness etc, which is why some coh2 1v1 top veterans fail in team games any mode bigger than 1v1
3. Let me word that better for you "good players of those modes don't get same reputation as 1v1 veterans" but that doesn't mean those modes are not competitive.
You are wrong sir, those modes are competitive and there are some good players in those modes, just as there are in 1v1 mode
And you said u checked the top 20 players and they had 500+ ranks in 1v1? That actually means they prob play that mode as fun mode and not competitive!
Actually how many (not top 20) top 10 1v1 players do you want me to name you (I have seen their playercard that they had +1000 ranks in 4v4s?!! does that mean they are bad?! yes or no! it means they are good in the mode the like and play competitive