There’s an interesting thread over on the LOTRO forums where a dev basically asked players to make a wish list of what they wanted built into the game (within certain parameters), which just opened the floodgates as you may have expected.
Among loads of pie-in-the-sky wishes was a pretty practical suggestion: more quests in the 16-40 range. There was even a graph of solo quests per level to back this up:
The initial hump there is because you have three newbie zones, all brimming with 6-12 level content, but then it starts dipping as players are funneled to higher-level Bree, then Lone-Lands and beyond. While I’ve never run out of quests through the upper 20’s, the poster reported that it got incredibly trying to level up multiple alts through what is essentially a linear path through the mid-game. More quests in more zones = more paths to leveling.
Anyway, thought the graph was interesting, especially how it gets a LOT better after 40. Life begins at 40, right?