Well it costs in DO droplets, dev time and effort for perhaps limited gains right now at this stage, when the devs resource is IMHO better spent on completing the tasks necessary from the last test and the other planned features.
I could be utterly wrong but I think rushing into another testnet without thorough analysis of what we expect to gain/prove, what we can realistically test is just a waste of resources. Yes it keeps us mob happy but the team has a duty to get the job done for the whole community, not just entertain us hands-on junkies.
Im talking holding off a few days here, not weeks or months BTW 
I expect frequent testnets, which we as a community all enjoy, but its crazy to imagine we will get a new testnet every couple of days. I still think there are some significant items in the PR list Pull requests · maidsafe/safe_network · GitHub that should be merged before we indulge ourselves in another test net.
Having said that, none of the PRs has the large tag, most are medium. Note that 4 are waiting-for-review, which to my uneducated eye suggests that they are all too busy writing and testing code to check on each others work. Thats an oversimplification, of course but you get my gist.
I will be overjoyed to be proved wrong and given a testnet to play with tomorrow but realistically Thursday/Friday at the absolute earliest and we should also prepare for no new testnet until the PR queue shrinks.