Look, a lot of us like both PvE and PvP a lot. The people like that will typically have 3 character slots for their PvE characters and leave one open for a PvP-only character. That means there are only 3 different primary classes we can play in PvE, without deleting characters (and, as a result, deleting a lot of work invested in that character).
So, there are already 3 primary classes I cannot play in PvE without deleting my characters - not considering new classes and/or new slots from future accounts that I, of course, shouldn't complain about because they don't exist yet.

Here is my point. I understand that character slots require additional storage space on the servers. But ANet will gladly let us buy a second account for $50 and give us 4 extra slots with it. The problem there is that everything is separate between the two accounts - storage, unlocked items/skills and so on. We also have to log on to a different account to play different characters which is tedious.
On the other hand, I would gladly pay more than $50 to add 4 extra slots to my current account (assuming they were around $15 per extra slot, that would be $60 for 4 more). Why is this not an option for us? That is what I do not understand. The fee for the slots would more than offset the price of the additional storage space needed for them.
ANet, let us buy more slots!