I remember having some of those reservations when I was researching them before sending my donation for the BC-Coinkite drive.
The bottom line was this: the investment was small in comparison to the advantages. Sure 25BTC isn't exactly pocket change... but try getting dedicated POS terminals and custom software written for BlackCoin - for
less than that, or for that matter for twice that much.
I rolled out POS systems for a client some years ago and the deposit for Verifone on 5 stations was something along the lines of $25K. That was the deposit (kind of like a bond or good faith deposit actually). Sure it wasn't gone forever, IIRC they would get it returned to their account after 24 months of operation - during which they'd be paying 3.5% on all of the transactions!
I think the merchant services have gotten much better with time and competition, and I'm sure the advent of smartphone kits for POS and services like Paypal cut in to their nice little extortion scheme... but at the same time - my client was more than happy to pay, because taking credit/debit card payments would boost sales by 30-40% per month.
However, the real justification is simply this... with coinkite, even if there's not a single placement yet, BC has an answer to the question "what can I buy with it" - or for a B&M shop "how can I get paid in it". If I felt there was a possibility that the BC community could have developed their own in-house solution in less time... I might have argued against it as well.
But I think we all know that we're incredibly young, and relatively unknown still - so while some other very large communities might have the talent, and others might have the value... we had little of either at the time, and this seemed like a good interim solution. Besides Coinkite is present and often a minor sponsor of many crypto currency conferences... so we get some side-promotion for that investment as well.