also now that i think of it:

2. there is now a discovery mechanism of some sort… but otherwise it’s a feature and not a bug that you can only identify people whom you had an initial exchange with. much preferable than something that Signal that without asking (and without opting out?) will by default access all your contacts and match them through the use of a strong selector (phone number) also:
3. i think with the minimal knowledge the server has of its users (and the no-identity concept) this really limits risk. Also it means that for the most tight of security models, one can use their own server (which is not feasible with most other chat protocols)

so all in all: go simplex! :)