I don't see the problem with the low ilevel requirement, the ilevel is there to prevent people from getting inside too low, in a realistic setting, a group won't have that ilevel and would be 10 levels higher to "normally" run it. Rewards? Yoshi already stated the rewards will include the new allagan tomestone, there might be more to it.

Now for difficulty, I don't see the problem with it, it's not an end game raid, we have coil for that, these new dungeons are designed for ordinary players, it's also a means for new players to catch up with the people from launch, if it was made too difficult, new players will be turned off by it because they'd have to gear up for a dungeon to gear up for an even harder dungeon to gear up for end game raid, a great majority will not want that, I certainly don't. If difficulty is really an issue for you that you might steamroll it with your current gear, then why not find like-minded people who want hard content, and just do the dungeon with weaker gear?

Oh and if it's any indication. Pharos siruis' 1st boss, Turn 5, and a number of other dungeons, "punish" you for DPS-ing too hard, forcing a phase change in an untimely fashion, and from my experience, it makes the encounter harder than it normally would be. If the dungeon follows this style, you might be in for a surprise when you do the dungeons once they come out.

TL: DR
The dungeon isn't meant to be (incredibly) hard, they're designed for new players to catch-up with the rest of us without having to go through an insane amount of grind, thinning the gap between hardcore and casual players, while providing a bit of challenge.