It's an interesting exploration of weight class over time.
At no point is a com morph being efficient (exception, first level morph) compared to its weight in units. An independent worker is better than a nanolathe. A dirtbag is more efficient than an ablative plating. A dante is better than equal cost in battle com. A catapult is better than equal cost in artillery com.
There are a few advantages though:
Weight class - At the start of the game, there is nothing as big as a com. So long as you don't lose it, you can gain a decisive advantage just by attritioning lower weight units then retreating. Each subsequent module benefits from the protection of this weight-class, but this must be compared to the scaling of the units around it as economies take off.
Immediacy - The com is already on the front line if you want it to be. No travel time for your investment.
Micro-installments - Coms are built in short bursts, meaning a granular progression. You get to make use of your investment earlier and there's no risk of having it sniped in fac. You also get to adapt on the fly. Scout a wyvern? Get a single ablative plating on your sup com.
Ambiguity - You scout a dante you make ravens. You scout a morphing com your options are more limited because you don't necessarily know their intentions.
Module synergy - Base inefficiency can be mitigated by investing more heavily in synergistic modules. The value of dps goes up with range and vice versa. Now that coms are uncapped, this means coms can actually have full sets of multiple modules, instead of one or the other.
Flexibility - I'd pay 150 more to put a nano on my dante. Making it amphibious would be good too. Invisible? yes plz. Jumping? Aww yiss!
Despite all this, they are outclassed pound for pound. If you want to make coms work you need to be taking full advantage of all the small things, because its an uphill battle by default. If you're against a troll com, know that, so long as it hasn't killed a bunch of stuff yet (see: suiciding), it represents less of a threat than whatever you spent your metal on. If it's a really big com, does it beat krow? Bantha? Racketeer? Raven? If they support it (they need to if they want to make it actually difficult to kill), add the cost of that support to the com. How much on AA did they spend to protect it? How much on screening? I'm yet to see a com+support that was unkillable assuming equal investment. If you managed to take more of the map, you had more to invest, which means it should have been super killable.
Also, if you're complaining about a particular happenstance where coms felt OP, you need to link a replay and let us judge for ourselves.
