Well perhaps, but considering that cleansing is stable element of healing in PvE, being featured as a nescessary component for many encounters, it would be rather difficult to remove cleansing all together without just "dumbing down" the game.
Agreed. Which is why uncleansable DoTs exist. Cleanse is perfectly fine in PvE encounters, but it is overpowered against DoT specs.
As for direct damage, I disagree that there isn't a counter to that. I'd say that there are in fact loads of counters to such abillities whether they're delivered instantly or channeled. LoS'ing/Kiting/Physics(e.g. Push/knockbacks etc)
Line of Sight - This is only for activated direct damage attacks. Melees have very few to none of these. Only a few specs of ranged have them. So this isn't a counter to instant direct damage specs. And to the extent it is, it is also a counter to DoTs as well.
Kiting - Balance Shadows, Pyro PTs can be kited. This has nothing to do with DoTs v. Direct damage, it is a function of range.
Push/Knockbacks - This is not a counter to an instant attack. Once the attack lands the damage is done. It's actually a better counter to a DoT spec. Often I will push a DoT spec away and run out of LOS. That gives me time to let the DoTs expire or for me to use a heal/medpack.
DoT effects outlast such counters to direct damage, if not cleansed, giving that type of damage a relative advantage over direct damage (based on circumstance, naturally)
That's not an advantage. What you're saying is that DoTs do their damage so slow that they outlast cooldowns while instant attacks just get eaten. Well, if you are crazy enough to waste your big attacks on someone who is using a 3-5 second cooldown then you deserve to lose. But DoTs have to apply their damage over 6-18 seconds. And for damage that is not superior to what direct damage specs can apply in the same timeframe.
DoTs have NO offensive advantage over an instant direct damage attack of the same damage type. For example, Discharge in the Deception spec suffers NO counters that Discharge in the Madness spec does not also suffer.
But it does seem to become a "hit-or-miss" issue where DoTs are either too simple to counter or too hard, while at the same time also becomming a problem of only some classes being able to counter them at all. The idea of a "backlash" or some form of significant cost to cleanse them, would be an interesting way to go about it, I feel though. Would encourage a more active approach to the issue of countering DoTs, where the one cleansing has to weight in "pro's and con's" of doing so, rather than just acting with a "knee-jerk reaction".
The thing is DoTs aren't any harder to counter than direct damage. In fact they are easier to heal through, can still be shut off by purge abilities and telegraph themselves for healers. People got used to being able to push a button every 4.5 seconds to shut down DoT specs, but it plainly isn't fair or necessary.