I will propose this theory. DAoC currently is more balanced towards caster than tank. They have range, good damage, and often their own forms of baseline and spec CC added to the quickcast ability that allows them to escape pressure from melee long enough to re-establish good position. They (mostly) have stat debuffs, which with the advent of power mythirians, the infernal sleeves, a myriad of /use MCL2 abilities, and increased stack size of power pots, are actually usable nearly every time they are off cooldown (which is, for most spec stat debuffers, 5 seconds I believe). Casters can cross-debuff damage, making a spec nuker and a debuff nuker a prime dynamic in a groups' ability to spike DPS onto an enemy target. And if you're still slow to the dynamics of PvP games, spike damage is what kills people. Casters, due to the power giving items which were added to the game, are no longer required to spec for MCL or RP. They can go full damage passives if they so desire. Essentially, casters need MAYBE some aug dex (saracen and lurikeen casters definitely do not need much, if any, aug dex to hit their dex breakpoints) to have their potential realized; everything past that point can be spent on damage which will only make them more potent. Casters do not have to spec for power-giving abilities like MCL or RP. DPS casters likely forgo Physical Defense in favor of damage increasing RA's. To be competitive in RvR, a caster needs little more than purge1, LW1, enough aug dex to hit their breakpoint, and then can begin stacking damage passives.
Now, look at this from a tank perspective. Tanks and light tanks of any kind are very much NOT RvR ready out of the box at 50. They have to spend points in Det9 just to be able to avoid uselessness due to CC. They have to spend points in charge, simply to catch their target most times. Once they have spent points to max their charge and Det, they still have to worry about caster damage (which, once resist debuffed, is actually really frickin' high), so they temp things like magic resist charges from dragon rings or add points to AoM and Tough to increase their survivability. What this results in, is tanks which spend most of their RA points on survivability and CC dampening abilities, whereas casters can charge full ahead and dump 90% of every RA point earned into raw damage. After all of this, in the current balance of DAoC, tanks end up being little more than glorified interrupt bots for the amount of time they can hit their target before being destroyed or peeled off.
Aside from what I have listed above, I believe this issue is created by the patch that increased the clip range in which people were able to see enemy targets from beyond normal spell casting range. This patch, in essence, gave casters the ability to split apart, drop speedwarps, and gain ground before an enemy group was able to so much as throw down insta-CC. There is little way to catch a wary caster on incoming and force him into the ground before he can become an issue. I understand that this may be a cutthroat view on the caster vs tank balance situation, but it's one that needs to be examined somewhat. Casters, IMO, currently have way too much in their favor, and clip range in its current inception is one of them. They are able to notice a fight before it happens, get in good position before either group can really actually do anything to the other, and on top of this their characters only get better with RA points, whereas tanks only start to become "viable" after dumping a large amount of points into Det9 and Charge (if available).
I'd like to see some means of forcing casters to spend points into RA's other than damage passives (MCL and RP are pretty much never seen in a standard caster RA template at this point), or something done to help the tanks actually engage the enemy group before they are whittled away to uselessness through death or stat debuffs. And yes, ideally I'd like to see the clip range reduced somewhat; the game was designed around the old clip range, and having the inability to do anything to an enemy group at first sight makes the head on incoming moment a little bit less tense and more of a stand off until someone makes a mistake.