The problem with unrestricted short rests is the Warlock-type classes that regain most/all of their abilities/spell slots/dice back on a short rest. I mean, my main is a 'lock so I'm ok with that, but it makes the game esaier if you can do that.
2 per day, as mostly everyone has said, is truly the optimal amount, otherwise you can have a party of warlocks and battle master fighters and just cheese the game.
Currently you can cheese long rests.
I imagine that will be fixed though. Aside from that, the warlock class in PnP typically relies on having more short rests being available than 2, any game I've been in warlocks dictate a required short rest after just a few encounters. While casting EB every turn for 5 or 6 encounters in a row lasting 20 mins each is amazing fun and all but typically, they like to use at least one turn doing something else. At higher levels DMs get more restrictive on this but lvls 1 - 10 short rests are really common with a warlock in the party and the reason is simple, if you're restricted to 2 short rests between long rests, the warlock class becomes deadweight as anything other than a dip class in regards to combat. Limiting to 2 is just wrong. Plain and simple. There is no refuting that and any DM that says otherwise should talk to their warlock to see how they feel about it. Restricting your players to 2 means your pure warlock player will feel like a fifth wheel half the time in combat and on a road to boredom the other half.
Warlock is designed to use a fair number of short rests, this is why the limit of healing during a short rest is decoupled from the short rests themselves.
On a further note, people highly overate the negative impact of cheese. This game is using the BG name. Two games that can be cheesed to high heaven in a vast number of ways. Seriously there is an insane number of cheesing methods you can use for various aspects of those games. In reality however, most people don't cheese because unless you're specifically setting out to engage in cheesey silliness it's just not fun.
I've killed firkraag with hundreds of thief traps for a laugh, and most of the tougher baddies in BG2 and ToB, but I've played through it far, far, far more times without cheesing. Using and abusing cheese in a single player game is a choice that a player makes, and anyone that does it to get through the game on their first playthrough, clearly isn't put off by a lack of challenge. As for the multiplayer aspect, its not an option because either everyone's into it, or someone gets pissed and leaves the other to it. In DMed multiplayer or persistent worlds or any other multiplayer setting this sort of cheese is restricted and I have no doubt that anyone capable of building such modules/stories/servers will be able to limit such behaviour.
Cheesing is really a non issue.