I used it too. I miss it, but i get why they removed it: it just kinda breaks the Signal user experience and trust model. This app lives and dies by the users trust their conversations will be private. By having an option to message someone in a completely unencrypted, easy to intercept mode like SMS it risks this trust for little gain (some power users like us liked it). By removing it, the app concentrates on what is expected from it and removes a big possibility for user error while fleshing out its marketing image even more. It makes perfect sense but its a tad annoying.
The American embassy for McDonalds