At this point pilot levels and mech ranks are a bit ... meh. They lock new items and internals and that's it. As I have understood, this forum has always been strongly against vertical progression (high level always beats low level) and so am I. There have been a few attempts for horizontal progression, I can talk only from beginning of open beta, but old beards can shed some insight to earlier days of Illal.
Pre-ascencion there was the skill-tree with braches for offence, defence and mobility. This was sort of vertical, but the buffs were quite small so they really didn't matter that much. Also, only few builds were good enough to make a difference.
During ascencion we got the optimization points, which allowed pilots to buff cenrtain abilities of their mechs. This led to drastically different instances of the same mech. Air-zerkers anyone? It was very difficult to know what you were up against.
I would like to see the optimization points restored to some extend. Maybe so that with levels you get tweak points, which aren't actually buffs, but would allow you to change one property to another, i.g. change armor to speed. So more levels/ranks would allow you to divert your mech more from the vanilla version. This would allow guite easy balance tweaks for devs as they could adjust, not just the base values for mechs, but the magnitude how much one tweak point would alter said value.
This is a rather raw idea, but post your own opinion, how progression should work! Or fill my gaps how things used to be, or comment my idea.