The predictable monetary supply of Bitcoin is precisely why it is doomed to fail. Specifically, Bitcoin's deflationary nature.
In the best case scenario, Bitcoin will continue to experience unstable boom-bust cycles as prices will rise when people start hoarding their coins, then crash again when people dump their Bitcoin en masse once prices hit a high enough peak. This is great for speculators, terrible for everyone else.
In the worst case scenario, Bitcoin prices drop to $0 when everyone gives up using it. Which leads to the second problem: Bitcoin never really solved the chicken-and-egg problem. Not enough merchants accept Bitcoin for customers to bother with yet another currency, and not enough customers use bitcoins for merchants to deal with yet another currency. Services like Coinbase are merely abstractions over the USD - too few merchants deal solely in Bitcoin, and for good reason.
The things that make deflation bad for traditional currencies don't necessarily apply to bitcoin. There are good arguments on both sides and no consensus like you seem to imply. This debate has been done to death so I'll defer to https://en.bitcoin.it/wiki/Deflationary_spiral.
Bitcoin is not ready for for pure bitcoin dealings, Coinbase is on the right track for now we need services that are basically abstractions over another currency.
Pure bitcoins dealing will start getting adopted by the average folk first once the availability and ease of use problem is solved.
In the best case scenario, Bitcoin will continue to experience unstable boom-bust cycles as prices will rise when people start hoarding their coins, then crash again when people dump their Bitcoin en masse once prices hit a high enough peak. This is great for speculators, terrible for everyone else.
In the worst case scenario, Bitcoin prices drop to $0 when everyone gives up using it. Which leads to the second problem: Bitcoin never really solved the chicken-and-egg problem. Not enough merchants accept Bitcoin for customers to bother with yet another currency, and not enough customers use bitcoins for merchants to deal with yet another currency. Services like Coinbase are merely abstractions over the USD - too few merchants deal solely in Bitcoin, and for good reason.