Only you can answer this and it comes down to how you want to design your shard and how you want it to function. It also guides the course of how you want player characters to be. You can have the extreme of no-cap and then a single character can master every skill. This may have players make less characters. So do you care if character master every skill?
Also, isn't the cap 720? Regardless, the 700ish skill cap is meant for players to create a particular character class-type like a ranger, fighter, wizard, or thief. Characters with limited skills encourage varying play styles as one would play a heavily armored fighter much different than a wizard. So, do you want this style of play on your shard?
I have run shards that had no skill cap and I don't recall anything being game breaking about it. If you have a low population shard, then allowing characters to master every skill makes the game single player friendly...without having to change other mechanics. I simply moved away from the unlimited skills due to my particular play style and my outlook on what a fantasy role-playing game should be. So decide what type of game you want to run...and more importantly...what type of game do "you" want to play?