There's a system in place (or at least used to be), where you'll get kicked from the Battleground and hit with a deserter debuff - which lasts for 20 minutes in ESO - if you go long enough without doing anything. Back in the days of "infinite" loading screens, this was a source of ire for some people.
Anyway, 10 seconds from spawning until getting kicked is definitely too short. as @_Ahala_ points out, sometimes it would be a big tactical mistake; if another team is in your team's spawn, and you're the only person that has rezzed yet, jumping down most likely just means you end up "feeding" the other team. And to add to his list: what if you're in a group of solo queued players, and need to type something to your team? If you're going to try and work out a little strategy with them, you may very well need more "safe typing time" than that.
Being able to nuke people from your spawn is somewhat of an issue in some objective-based games (in Deathmatch you can/should just back off), but I can't agree with a forced leaving of spawn within such a short time of spawning.