I personally don't think it's flawed, but it's certainly different. As I mentioned, there isn't really anything stopping you from opening your FP inventory manually and loading packs into the bar from there. Considering 2s and 5s are typically only used as one-off drops or to round off large donations, I guess I'm not really understanding how this 'reduced control of pack usage' is somehow such a big deal when the majority of the time we're using 10 packs anyway. Unless you're making triple-digit donations using nothing but 2s and 5s?
The next event is an excellent way to show how flawed the new GB window is. You will receive quests that say spend 5 FP. Ok... go to a GB hit the 1 button 5 times, it will open 3 2 packs, you will have wasted one on the bar when you could have put a 5 pack there before.
You will now need to load the bar with FP for every quest.
It requires you to load points on your bar, then spend them. But make sure you don't do this out of order, add all packs to the GB before you put anything on your bar or you'll screw yourself. IE if you have 2 on your bar and need to add 17 to a GB. The logical thing would be to spend 1 10 pack 1 5 pack and the 2 from your bar right? Here are the steps that are now involved with that:
Load GB
Hit add 10- 2 will be removed from your bar, 10 removed from inventory,2 will be put back on your bar.
Exit GB
Go to bar and add a 5 pack
Re enter GB.
Click empty bar.
Or you could drop the 2, add the ten exit add 5 to bar reenter. Saving you 0 steps. Essentially there is now no way of spending 5 packs than loading them into your bar or running out of 10's or 2's.
Run out of 2's? Great, now hitting the +1 button means you waste 4 FP instead of 1.
That is now a 6 step process. Essentially they just reversed the issues from mobile on to browser. The complaint about mobile was having to load points to the bar to spend, now that's what we need to do too. Unless or until they start treating inventory FP as a FP pool this is the most convoluted system I could imagine.
Add 10 button is great but wasting FP and having to constantly sit there and math out how you're going to add exact amounts to GBs without wasting points with this new system is horrible.