Plus he's only actually led it for a few years. For some many millennia, they've been on their own in the Eye which would lead me to think they might prefer something a little more subtle then a cluster rocket launcher to remain unnoticed for so long.
The Phoenix Lords have pretty crappy models, cept for Maugan Ra and Baharroth. Not just crappy models (they're old models, to be fair) but I don't particularly like their designs either. The much more modern Autarchs look a lot better.
The Phoenix Lord models had not changed sense they first came out. The only change you ever normally see to Jain Zar occasionally is someone remodels Lelith Hesperax to be her.
Didn't they state that the starting leader of the Eldar faction would be Jain Zar, but that it could change after a time period/set amount of campaigns? Meaning that a year after release the might change the faction leader? It would be cool if they wrote a short/"medium" story about Maugan Ra and his attack on "bla bla bla" on Arkhona, here he would then die/be captured and the Eldar faction had to retrieve him and the Eldar Soulstones. I wonder of much rage I am going to hear for suggesting that Maugan Ra "loses". I, at least, would find it entertaining if we got such an important quest, essentially it would "force" us to take a certain territory, which would otherwise be useless to use, an maybe the other Factions had some interest in preventing us from completing the quest? EDIT: They could also have us find an artifact of some sort, which Jain Zar needed to guard during its transportation to X craftworld, leaving us in need of a new faction leader.
I don't know if they did say anything like that, but it would certainly be cool to have different leaders to show up from time to time and hear a different voice telling us what we're killing for this week.
Agreed - you could even do a relatively simple storyline where you help a relatively low-ranking officer get to a high-ranking officer by winning battles under them (whenever they are the voice-over explaining the map/objectives) - and as they win more battles (the voice-overs we players are ostensibly operating under) those NPC Eldar steadily gain or lose rank (essentially at random) but caused by the player's performance while they were ostensibly acting commander of each map. Anyway - that's more a long-term way to tie RP into an FPS experience - but I'm thinking something along the lines of Titanfall's story mode.