Actually, the fact that they are an existing business lends them a certain degree of credibility. It's not one of those anonymous groups we know nothing about who will likely raise money in an ICO and the disappear forever.
These folks run a reputable, successful business already and want to expand. That puts them ahead of the crowd in my opinion.

Regarding your question of "why would they want to raise money since they are already making money?"
Businesses do that all the time! Starting a business, proving it can make money, showing that it could make even more money with some additional funding for expansion, and raising another round of venture capital is common practice.

The final reason for them to do this is that it allows cryptocurrency/smart contracts for sales. This allows things like safe, peer-to-peer transactions, reduced transaction costs, etc. I think any online marketplace would benefit greatly from a well thought-out strategy for leveraging cryptocurrencies.