Free to Play Tier Mechanics Thread - Critique

In some free to play games where planes or tanks for example are unlocked over time, later tier things tend to have increased repair costs eventually to the point of being unsustainable. I've even found it to be more fun to stick with lower tier stuff in these types of games as income becomes a major issue, as does the change of vehicle which often is not even all too much better when you consider the great price you pay to use the damned thing. In a way it entirely defeats the point of the tiered system.

Anyways point being: Are higher tier planes, ships, tanks, ect even worth getting if mechanically they're often not significantly different so unreasonable to use you can't even get a hang of using them without going poor?