On one hand, I think it's a great idea to deter spam profitability. But on the other hand, the impact on minnows would be great. Legit new comers already struggle for their pennies, especially when new account delegations have been slashed down to 14 SP. I often get users freaking out why they haven't received their payout worth in pennies, only to realize they're simply too eager to earn and didn't wait for the full 7 day period to elapse.
Considering the increase in users from poor countries, I feel it would be a devastating experience for them to increase the threshold to 0.10 SBD.
I think spam should be also addressed with better algorithms to throttle posting. It's nothing new, such mechanisms already exist for email spammers, why not have the same on Steem?
Throttling frustrates power users who move quickly responding to dozens of mentions, comments and posts about me or my projects every day, but if it meant that spammers were throttled by IP, say on a time-increasing curve with each post, woot woot, and such, same could maybe be done for signup.
rule per ip address:
first comment/signup immediate
5 second timer
second comment/signup
10 second timer
third comment/signup
15 second timer
etc perhaps.
all the way up to a 45 second delay
then if you wait 60 seconds after last comment/signup submitted, then reset the clock.
Wisdom. Also, users of the other apps built on the blockchain could be widely negatively affected by such ideas. Imagine the drop in innovation.