I was waiting on expert mode as well and was kind of disheartened at the change. The thing is no one knows what 1.13 will be, just like they didn't know what 1.12 would be, other wise they would never have started on expert mode back in April. So to say something like 1.12 is a good stopping point is kind of pointless because if Mojang comes up with something just as good or better I can already hear, of 1.13 has this great new feature that going to totally be awesome forget what we said about 1.12 or 1.11.2 or 1.10.2. My point is why scrap 3 months of work? if I were to do that in a company and say hey this new software came out so we are going to scrap this, I am sure this new software is going to get us where we need to be, don't worry about fact we are flushing 3 months of development. My personal opinion is finish what you started, give Lex and CPW time to stabilize 1.12 in Forge before beginning development on the next generation. If 1.13 has something even better then 1.12 what then??? More nostalgia map rewrites while you drop back and punt again? To not finish what you started is a waste of time and resources unless you never intended to finish it anyways. Just my .02, it might not be the "Wow Gee thanks for all the great work on free stuff FTB, but it is what I feel like now. How many mod devs and mod pack devs are going to get burnt out trying to keep up and say screw it and move on?
That sounds great and is an answer to why 1.12 will be interesting for Modding at least for Expert Mode. But for normal none Expert modes I do not see that this will do much in the first months. Mods are currently designed without this in mind and materials and recipts are adapted due to the fact that you have all recipts available from beginning if not blocked by the mod itself already with a Tier system.
For me that I was waiting for the Expert mode to be released in the next month or two this is bad news so far I guess.
Mod developers won´t redesign their mod completly to this new crafting system. And if they do, it will take time. If we are already strugeling to keep up from 1.8 to 1.10 to 1.11 then I can't imagine that such a redesign would do any good in terms of time
FTB-Modpack team might be better of by waiting for 1.12 and the Crafting system for an good Expert mode, but they can finish the modpack once the mods are updated so...
Guess before september we won´t see anything <-- not blaming anyone for this really. Just saying.