$2.99 is essentially three times $.99, so a steep number. The $.99 per app price/standard was somewhat arbitrary to begin with, but that's what we're all used to.
$2.99 a month is essentially $36 a year, which is definitely a price people would balk at. Software subscriptions are a thinly-veiled plot (generally) to stealthily get more revenue for the same amount of work. I don't feel like 1Password has increased the frequency of releases or improved the product commensurate to the added revenue they're theoretically getting.
I mean, I use 1Password (don't subscribe), I like it a lot, it's very well designed and engineered, and I expect it to continue that trend, but the argument that this stuff costs money might not always fly with me unless I actually see something getting better. And in the case of 1Password, there's really not a whole lot of room for improvement, honestly.
I had the pleasure(?) of hearing Carl Bass speak earlier this year and he flat out said that the 'best thing I ever did for Autodesk's bottom line was switch to a subscription model'. It was all about revenue, and this is a sample size of one, but software subscriptions have not yet proven to be beneficial to the average consumer, that's for sure.
Traditionally most paid software gives you a short trial, so I'm not even sure I'm buying the advantage that subscriptions benefit users that need it for a short amount of time.
BTW, you rarely see software subscriptions implemented on software that's doing badly. In other words, the original idea behind it was that a company, like Autodesk, was seeing stagnant growth and found a way to squeeze more money out of the consumer without giving them anything in return. You don't usually see subscriptions on software that nobody wants in the first place, it's normally software that's already well established, essential to business process, a particularly addictive game, etc. There's a reason why the myriad solitaire apps in the app store don't try to get you to subscribe ...
So I guess what I'm trying to say that software subscriptions are consumer-unfriendly and are purely a method of increasing revenue on the same number of sales/users to benefit someone's bottom line.