rouge, warrior, dk, hunter agains cloth

We were playing on the server recently with a few friends, and we all bought coins to avoid the grind of leveling. We started doing arenas, but the game has become completely unplayable whenever we face warriors, rogues, DKs, and hunters as cloth wearers. They drop our HP in 3–4 seconds without us being able to do anything. This makes the game totally unplayable. As a caster, you have no chance at all. We've even considered switching servers. Are there any plans to do something about this, or will things stay the same?

Beatings will continue until morale improves (or you learn to play the game).

I'm not sure what do you mean with "do something about this." If you found something that is bugged/working incorrectly, and can back it up with evidence, you can always open a Bug Report for it to be checked and fixed, if confirmed.

Now if you're talking about custom changes to make classes perform better in PvP than they were ever meant to in the original game, no, that's not going to happen. The game has never been balanced so every class/specialization and combination of classes can be equally viable in PvP. Some are better, some require a lot more skill and experience to perform well, and some are just outright worse. That's just the way World of Warcraft and these expansions are.

Keep your distance and reduce enemy HP to 0 while keeping your HP above 0.

There's always fun blowing stuff up as destruction warlock+elemental shaman

In bgs you have a significantly better advantage vs melee as going into melee usually attracts massive aggro unless its a premade in which case nothing you play will change the outcome. For example if you had a full bis warrior or rogue you will still get cooked in bgs esp if its av, isle, or even wsg in certain situations. AB and EoS you have more flexibility because you have choice of engagements. Casters, by contrast do fine in every bg format.

In terms of arena, its about class synergy. For example a affliction ele is not going to do as well as a ele destro lock. You need to work as one class rather than two individual classes and vice versa. A hpal warr is a hpal war not a war and then an hpal.

Now vs hunter, it's a special case. They beed LoS just like you. The way to beat them is dots and hide or immune because they have no self heal.

Now vs warr, they have no self dispel and gap closer is 30yd range, use spells above that range with slows to help abuse this.

Rogue and dk are supposed to counter you but can still be beat with a combination of above tactics. But yeah if there were not classes to counter clothies like in later expansions game would be broken. It just happens to be in wotlk, anti-cloth classes are popular. You may ask, well what is supposed to beat rogue and dk? Preg/ret with 1h shield. Wotlk is pretty rock paper scissors in general but also remember game is not designed around 1v1 all things being equal.

Tldr;, wow is so dynamic given different scenarios, you have to think about where your strengths are best placed.

Also, in arena, watch vids of top players. Here are some examples.

For example Rivah #8 first sequence, just watch first battle as spriest frost mage to see the level of anticipation, how good you can be. Yet at the same time casters can be played at such a level the enemy has no chance.

Also for destrolock ele sham check out Chanimals. The level of CC and communication makes every 2v2 a 2v1