Its sounds strange that when you have a some "basic" (say hunchback/t34) unit and want to go to "advanced" (say timberwolf/is-3), game that lets you go straight at it if you want has "less content", but game that forces you to go through grinding and researching through several ranks with mandatory buying 6 units per rank no matter you want them or not has "more content". More than that, until you are in that elo part where only meta builds live, you can see any mech on the battlefield no matter what you drive. You can only see a little number of certain different tank models per rank. It gets stale much faster. More than that, there is often a little difference between tanks in a line, like panther A, D and G, but you need to pay progressively more money and xp for each next and start each time with stock.

Dont forget, that in tiered system player is pressured to progress by constanly having higher tiered superior vehicles present in same match, and skill means less against impenetrable armor and gun that one-shots you from 1 km through your frontal armor. Such system is "invalidating the entire game until you've hit the top end limit" too. At least in WT tiered system caused by more or less realistic depiction of tank/planes with drastically rising combat capabilities due to fast technological progress, unlike in WoT with arbitrary numerical characteristics. But in MWO (and in TT), lasers and armor are same between locust introduced in 2499 and locust introduced in 3030.

I dont think that you would play game, where, in situation where you like, for example, a jenner, and dont like locust, but had to grind tier 1 lct-1v, then tier 2 lct-1e, then tier 3 lct-1l then you got your beloved tier 4 jenner, but suddenly you begin to meet tier 5 cicada that has everything better. At least for long.