I'm kind of coming round to that point of view. Before they were implemented I was all for them. But now, I find them more of a turn-off than a positive. To put this into perspective, I must have my name on around 15,000 systems so I have tagged more of the galaxy than almost anyone else (not that you'll come across most of them this side of the galaxyI'm starting to feel like the "discovered by" tag was a mistake, it's really eating away at my enjoyment to arrive in some nice little nook of nowhere and see another explorer has peed in the corner already. I can only imagine that it won't be any more fun around the core.
Sure it is easy to find undiscovered systems even quite close to home. But if you can think of somewhere specific to go then when you get there the chances are you'll find someone else's name on it even if it's a long way away. For me, at least, that takes away a lot of the interest. Sure, even without the discovered by tags, you know that someone else has almost certainly been there but you can at least kid yourself that you've not just travelled 10,000 LY only to find someone selling souvenir T-shirts!