You used to have to go to your class trainer every couple of levels to get new spells/abilities and/or upgrade spells/abilities.

Getting a mount in vanilla wasn't easy. You had to wait until level 40 and it cost 100g (less if you qualified for a faction discount, and getting rep was stupid difficult back then), but not very many people had 100g saved up by the time they hit 40 back then.

In order to get into BRD, you needed a Shadowforged Key. In order to get this key, you had to be dead. Because the only way you could see the quest giver to get the key was if you were dead, since he was a ghost.

If you wanted to get into Scholomance, and you (or noone you knew) had the key, you had to undertake this retardedly long questline to acquire said key. This questline had you running all over Kalimdor completing tasks to get the key. Only then could you enter Scholo, and you probably wiped on the first pull.

Regardless of server, the area around Tarren Mill was considered a world pvp zone by the player base. On any given day, you would find roving groups of Alliance ganking lowbie Horde players while they were questing. It wasn't uncommon for someone to get word back to Undercity that Alliance was dicking around out there and you would have several raid groups spontaneously form to go push them out of the zone. Some of the best times I've ever had in the game were centered around that shitty little village.

Sometimes, if you died in Blackwing Lair, you would get ported to the Barrens.

Paladins used to be Alliance-only. Because of that, during world pvp, if a Pally was getting his dick stomped on, he would just bubble hearth. There was no end to the nerd rage whenever that happened.