Try not to attribute forum comments to manufacturers.
So your argument is that because a different company changed it's position quickly Apple will do the same?
Let's see.
G4 - when it launched (1999?) it was about 2.5 times faster than the equivalent Intel PIII. In the intervening time the market moved on. It's not like Apple switched the next year, it was almost 10 years.
3rd party apps - Apple didn't say "never", they said they didn't see the need for them. However, once the phone was out in the market, it became clear that there was both a demand *and* a need due to patchy network coverage/battery life. Oh look, they changed their position based on the evidence. How dare they!
Multi-tasking - Again, they didn't say "who needs that?" they said that they thought it would drain the battery too fast and (quite correctly) it can cause stability problems in the OS and other apps. They wanted to work out if they could do it in a way that avoided the pitfalls, which they claim to have done for OS4, we'll see in due course. It was the fanbois to said "Who needs it?" and I have to say for probably 90% or more users they're likely to be right.
Cut & paste - Again, Apple didn't think people really needed it, but they reacted to the market.
MMS - As far as I know they have never said anything about MMS apart from the initial "It isn't available" and the "here it is" when they made it available. Again, I suspect they didn't think anyone really needed it - I've only ever sent one MMS in my entire life and I've only ever received two that weren't marketing crap. Even my service provider appears to have quietly dropped "picture message" bundles from its offerings, which leads me to suspect that not many other people are using it either. It's entirely possible that the people who were most likely to use MMS now just upload their pictures to FaceBook (or whatever social network their friends are on).
Quite apart from anything else, trying to lock down OSX to an app store after it's been on the market for so long *and* already has a reasonably large software base is likely to be pretty much impossible, especially as anyone really huffed could just load another OS on the machine and walk away.