I agree to Tarik.
I think that other pieces of code took more time and power than expected - i.e. proxy. A brilliant feature which some other products to not offer. Proxy got a lot of votes. Therefore PM has decided to go for proxy first. If they would known that this feature will block the whole team, maybe PM would have selected two, three or even more features to deal with instead of proxy.
Nevertheless signatures are important and my customers need it too!
Very curious as to why this hasn't been addressed yet. Maybe instead of fighting all the other competitors to develop a better and for useful product, the game plan is to have no features so you can chase what is left of the customer base away and then not have to "develop" the product anymore.