I’ve read how some people say you should just focus on a single class that fits your playing style. That might be fine but I think that’s like saying you should only be allowed to date within your own ethnicity. Hey, maybe you like fucking mannequins to help reduce the population growth in order to satisfy your urges. But that’s kinda besides the point.
The thing about having alts in World of Warcraft is not just for a banker. I see it as adding variety to the game. Not a lot considering that the playing style between most classes to not differ dramatically. However, it allows you to familiarize yourself with what people can and cannot do. In PVP without question, knowing each ability is critical as you will learn how to counter other classes (potentially) whenever they use a certain type of ability. Similarly, in group settings like raids, you can help advise others to fulfill their roles like using certain types of buffs, auras, CC and interrupts.
For myself originally, my primary reason for taking multiple alts and leveling them to 85 is that I wanted to max out all the professions. At the moment, I cover all the professions and have managed to max each of them out. But I took this a step further to include lock picking and creating portals via a mage as part of the whole notion of professions. That means that I can handle virtually every situation. I’m still working on my rogue but I’ll have that part covered fairly soon (at the time of writing this post she was at level 78).
Another reason to do this is that it helps with accumulating gold. Think about it in several ways. First, by taking and maxing out all professions, you essentially create your own industry. For instance, your jewelrycrafter can utilize your alchemist for creating meta and blue gems. Very useful if you have tons of green reds lying around. Then with your jewelrycrafter, you can take any useless excess yellow and orange gems and convert them into rings and necklaces for your enchanter to disenchant for materials. And as you level up and accumulate cloth, you can provide them to your tailor, etc. By doing this, you’ll find yourself spending less time at the auction house and more time being self sufficient. And if you do hit the auction house, it’ll probably be because you’re selling off the stuff you created and accumulated.
Next, I like doing this because I enjoy gearing each toon up. As a consequence, I make a fair amount of money per week. With my schedule, it’s impossible to run every LFR and Heroic HoT instance. So instead, I ended up running in groups of 3-4 toons per week. The thing was that once I hit 85 (or had a spare 85 some place), I would gear them just so that they could get into the HoT Heroics. I’d ask my friend to help me out since his DPS is pretty good and could cover my shoddy DPS. After doing the first three runs, I would get enough gear typically to become more independent. Ideally, I would run all seven first, then hit the first section of LFR in the hopes of securing a piece of gear. One side effect is that I would also get justice points and gold, leading to a few key pieces of gear (e.g. necklace, rings).
After a few weeks, my toons would be geared enough to carry a certain level of DPS. Then I could help others who had low item levels but with the bare minimum to enter HoT Heroics. If you keep doing this, again you discover that what you’re doing is creating an industry for yourself. Doing LFR and HoT Heroics each week tend to bring about around 700-800 gold. So if you multiply that against 3-4 toons, you’re easily looking at 2100-3200+ gold per week. And don’t forget with all your excess justice points, you can purchase BoE epics that you can sell on the auction house for anywhere between 300-600+ gold.
And for those that enjoy optimizing their time/gold/professions, you can utilize that time waiting for LFR and Heroics to pop by going out and farming materials. In my case, I have three maxed out miners and two maxed out herbalists (and one maxed out skinner, but I don’t play him much anymore). With those five, I would often run around Twilight Highlands to pick up ore and herbs. Since one of my mine is an engineer, I would grab additional volatile air, which is pretty tough to get without farming elementals. By doing this, I found myself getting around 200+ ore and some decent amount of volatiles. The ore I would hand off to my jewelrycrafter while the vast majority of my volatiles would go to my alchemist. My jewelrycrafter would prospect all ore, keeping the blues and using orange and yellow gems (and occasionally purples because I have a ton sitting in my bank) to create rings and necklaces. My alchemist would focus on creating Truegold with pyrium bars and the volatiles. As a result, I never have to worry about buying Truegold at the auction house.
Sure, this method is time consuming overall. It takes a great deal of dedication to get to the level I’ve managed. But is it worth it? I’d say it depends on your personality type. I enjoy being self sufficient and I love experiencing different classes. I find it fun being able to gear up as many different alts as possible to see how effective they can become. Will I ever do normal raids? Probably not. But I do feel that by the time the expansion rolls out, I’ll be sufficiently prepared to tackle the beginning. Sure, you may argue that the greens from the starting zones of the expansion will be better than your epics down the line. But that might be in a level of two. If you have some guy with just questing greens from the previous expansion, they still might have some issues fairing decently. So it might be worth investing some time into getting enough gear to not get too badly crushed at the beginning.