I've never used an intro (because I genuinely can't want to hire someone to make one and I don't have the time to learn how to make one myself) but I always introduce myself at the beginning of my video! Personally, I don't mind intros unless their incredibly annoying (blasting dubstep or EDM music and just overly flashy; think Ali-A on steroids) but I just don't think they're 100% necessary! But that's just my opinion!
Personally, I think that one SHOULD have an intro.
A short, a fast - paced one, perhaps, but definitely should.
It just looks more professional, with time makes your name more familiar to the audience (after all, you're creating a name for yourself with your content; a brand). For me, that 3s intro shows me you're taking what you're doing seriously.
Now, if we're talking about 10s+ intros - then I'd say go without one at all.
There are a lot of topics already made explaining why is that such a bad decision, so I won't go into details.
IMO, have a couple really short highlights in the beginning to catch a viewer's attention, a short (6 second or less) intro that's entertaining if possible, and then the body of the video. Establishing a connection with the viewer in the first few seconds of a video is necessary for those longer views, then you provide the branding so they know who they're watching. The intro can be subtle and still catch attention, but if it's dull or annoying you might end up losing views over it. I learned this on a previous channel I ran some years ago.