Well lock on it can be argued all time

For me i dont care only use for lock is in hand of newplayers actually in warrior's duel dosent help's

Assasin's can actually whine on lock becouse of stealth and as well vs bomb lock +run on target

However, this comes with a catch. Using lock makes you less mobile, makes your moves more predictable, constrains the freedom of your moves: These factors all lead to one fact: Your avoidance sucks. Avoiding the enemy missiles/hits/bombs/whatever the heck can harm you is one of the most difficult to learn, but one of the most important things for melee classes. So basically every single advantage you take of lock leads to a disadvantage as well.
A few examples:
-Locking on a mage? You will hit him easier, but he will kill you extremely easy with basically everything (given that the mage is not out of stamina, in which case he would probably die anyways)
-Locking on an assassin? Yes, you will prevent him backstabbing you (in 99%of cases), and yes, you can hit him easily, and yes, if he cloaks you can follow him without losing him- but if he has bombs, you are dead.
-Locking on an archer? He can hit you very easily, a target running straightforward to him is a feast.
-Locking in a warrior duel? Yes, you will be harder to hit and you will have a lower risk of missing your own stances and therefore taking a hit; but a good warrior can take advantage of your lack of mobility and hit you with side-attacks.

Besides, another big disadvantage is that lock is not reliable. It often happens that you press the button to lock and the enemy actually does not get locked (leads to confusion), or that you cannot unlock a locked player (deadly in many situations, some of them are shown above).

I presumed that the opponents are rather equally in skill (otherwise the discussion is pretty much senseless anyways) and rather experienced players (I guess that these are that matter, I doubt that we'd adjust server settings specially for new players- which are taking the most advantage of lock anyways, simply because the cannot hit properly without it).

As for Clanwars:
Lock loses more and more importance the better the players are (because good players can counter it and use these disadvantages extremely well), so I guess that this question doesnt matter a lot in CWs anyways.

I know it, because I remember the time when I started playing very well (it is not as long ago as many of you guys :p)
If you start DM, you simply have trouble hitting an enemy in melee, because nearly no games have a melee fighting system. The MP5 from Counterstrike isn't that much different from the MP45 from Call of Duty XYZ. I was a full-lock warrior in start; and i had rather many kills rather quickly- but almost ALWAYS as many or even more deaths; simply because my avoidance sucked.

I actually stopped locking because of you, Jil, because you explained me (as mage) that I could be a lot more effective without. Besides, I wanted to join EYE, and I actually thought that I wouldn't get into EYE if I locked, heh.

The problem here for me is that the archer usually gets some distance between him and you (sprint+long jump), and that you are still locked to him, while he can aim at you. If unlocking works, then it's fine, if it does not work, then you are pretty much dead.