Who are creating all the alternate cryptocurrencies? Everyone knows Bitcoin and Litecoins goes hand in hand and they are the most popular cryptocurrencies out there. But who is creating all these alternative cryptocurrencies such as Feathercoin, Peercoin, Quarkcoin, Craftcoin, etc. And why are they created?

I see no potential why they would be something people would want to pay with in the future. I can not think that a café (for example) wants to add any other payments besides BTC and LTC and some FIAT money.

Why would they ever struggle with adding Peercoin, Quarkcoin, Craftcoin etc etc etc?

Once again, who are creating these coins and why? Do they have potential to grow high? If so, why?
Many people have an interest in cryptocurrencies - some of them are interested enough that they would investigate and work on creating a new cryptocurrency.  Some people are in it for a quick profit, i.e. the scam coins, but others are genuinely interested.  Sometimes it is good to be associated with a currency, but often they prefer to be anonymous (to some extent) and watch and help from the sidelines.

A cryptocurrency is not just a once-off effort.  There is work needed to maintain it, especially when a problem occurs, or a security issue affects it.  It is necessary to update clients, maybe even fix a blockchain.

Another reason for the increase in alternate cryptocurrencies is due to the hardware investment in the coin mining community.  For most miners like myself, it is now almost infeasible to mine BTC unless you have or are prepared to buy into the latest ASIC miners, but even then, the timeframe for making a reasonable profit is very short.  What do we do with this hardware - we use it to mine alternate coins that suit the hardware.  USB ASIC miners for SHA-256 based coins.  GPU mining for Scrypt based coins.  Hence the alternate coins are actually filling a need by the mining community to have something to mine and have the chance to make a profit or get a return on their investment.