Removing the 20th Level Cap

Gamer asks why this cant be done:

Personally i do not like XP Cap.
I know that the 3° Edition of AD&D do not have roles for higher levels(more than 20) but, is there not not another solution?

Maybe the Single-Player Campagin can have a XP-Cap, but in the multyplayer section i think that the XP-Cap is just an ugly limit.
If NWN can give the DM the power to alter the EXP necessary to advance in each level, the Xp-Cap can be no longer a problem (or, at least, not so heavy).
I know that a DM cannot change the AD&D Rules but, it may be a chance to customize our own worlds even deeper.

…that there simply aren’t any rules covering play beyond 20th level and until there are (and they can be added to NWN in the future) there simply isn’t any point in doing away with the “cap”.

Cord Grimwinder