I think Concentration checks should be used to determine if a char is forced out of sneak mode due to taking damage.

If I'm sneaking toward the bad guy cleric and I happen to be next to Bob The Agro Magnet and the bad guy casts greater comand on him......I fall to the ground, but I remain in sneak mode and usually don't die from it.

If I'm sneaking up to a mind flayer next to my trusty pal Bob and get caught in the mind blast cone aimed at Bob, I am stunned but still stealthed and don't usually die because of it.

But If I get caught in a mass inflict wounds spell.....I'n instantly unstealthed.
If I stray between Bob and a gnoll archer and get hit (or even a near miss) from an arrow...I'm unstealthed and exposed to the world.

Seems to me I should be able to suck up the pain and remain in the shadows if I mae my Concentration check.

In general, I think skills should be more useful in DDO.

The Devs need to put things in dungeons specifically to use skill checks.
In general they should be optional, not required for completion.

But the high skill check goals should give nice rewards IMO.
Especially if it is a skill rarely used by players.

Also please increase the duration of Mermaids Splash spell.
This spell actually could be of great benefit in some places in this game....if it just lasted longer. Especially that shadow quest.
Or change the mechanic to allow casting it while swimming.

I also think that any Open Locks skill the char has should stack with the Knock Spell DC. It would make knock more useful. I'm all for Rogues, but no class should be required in a quest.

More optional secret doors. (random?)

Change the Find Traps spell to actually be useful for clerics. As is, the search DCs are too high for a cleric to ever reach even with this spell. Even a cleric who spent all his skill points on search and wears a search item will still not get his search high enough to ever warrent this spell in the game.

More uses for Listen. (Optional)

Skill DCs that are useful to a char who does not have the skill maxed, but has some points in it would be nice.