I am not realize someone who pays for convenience. I prefer the old style of MMOs with challenge which is hard to find nowadays. However, I see no reason why we can't pay for INconveniences in the store....
These are some things I would love to see in LOTRO, and would pay for in the store:
1. UI Option to remove visual display of numeric mob levels... I'd rather go by the text color alone
2. UI Option to remove radar entirely... currently I have it hidden behind an opaque chat window
3. Non-aggro breaks immersion. A character option for "no diminishing aggro radius" for mobs would be great! I know aggro is determined by the server, so it will need to be some sort of buff on the character. Perhaps a store item that places the buff on the character until removed by some complementary item?
4. Similar to #3, a character option for no experience gained when killing mobs or completing quests below player level. Different from the tortoise stone in that it doesn't require a slot and is a permanent buff (debuff?) to the character until undone with another item.
5. Option to scale down player damage to lower level mobs in proportion to player level vs. mob level. Also, scale up damage from lower-level mobs.
6. Ability to level up multiple professions simultaneously. Whichever ones we want. Seriously, I would pay BIG for this option as I am sure many other players as well. I could see paying $100 for this account-wide.
EDIT: 7. UI Option to turn down the game's lighting when in the night cycle. It's way too bright at night, a problem with most MMOs.
Those are some thoughts, anyway.