And even in cases where external capital makes sense, ask yourself why not get a bank loan, angel investment or VC capital if the business plan is sound.
Plenty of reasons. Most banks won't give bank accounts to Bitcoin businesses let alone loans. Individuals might not have access to VC or angel investor types. Even if they do, competition is fierce and the demands in terms of profit shares or shares of the company might not be favourable.
There's nothing inherently wrong with fundraising in this way (or similar initiatives - crowdfunding, etc), ignoring the obvious (i.e. securities laws).
Unfortunately, scams are scams and BTC-TC and Bitfunder shutting down hit the BTC unregulated securities markets hard.