Very good points!
In its current state, Bitcoin is definitely deflationary and as adoption/demand goes up, there simply is not enough supply to keep prices stable. All of this is ultimately code so it's possible, although highly unlikely, that more Bitcoin are eventually created, but for the foreseeable future as the popularity of Bitcoin increase there is only so much supply that can be met following traditional Economics of Supply and Demand.
The value of Ethereum and what appears to be it's long term value prospect is to be the building blocks of the DAPPS stack. A very ambitious and exciting prospect that will take years to develop and tune. While Ether is not deflationary like Bitcoin it can still outpace Bitcoin by having superior technology, but why have that argument, they are accomplishing different goals with different motivations.
RE: Bitcoin Payment Hurdles | Why Pay with BTC when you Expect the Future Value to Increase?