I understand that they are "nice for players" but I'd like to see the campaign-theme reasoning of why your world has them, but not standard D&D.
Ah, sure:
Extra Healing Surges: Well, I don't like short adventuring days a lot. I tend to run campaigns in urban and/or overland settings (sometimes combined), less dungeoncrawls. This makes extended rests a bit problematic - like during an overland chase, or if you're in a city (urban plots are rather event driven - and play in a rather short time frame, hours, not days). I could remedy this by making encounters less resource-draining (and hence easier), but I rather give them extra resources and keep the challenging encounters. The players like having extra stuff and feel more challenged, as every encounter can be deadly.
Furthermore, I watched my players for about three sessions with these rules now... with a fixed number of surges, they always know that they're probably not able to keep up and need a rest. With this... there's something tempting: Perhaps, with the new extra surge you have now, you can keep up, even if you're low on them.
Encounter Power Regain: Simply because it's interesting to use more than at-wills. And it helps a bit with the verisimilitude - it feels "right" that the martial-inclined characters can regain them in the right situation, like spotting an opening in your enemies' defense. Note that this is also true for enemies - this makes d20 rolls something exciting - for every side. Plus it fits the somewhat pulpy style I prefer... think Indiana Jones pulling out a last ditch trick.
Knocking Prone: Well, a bit because it's pulpy and interesting to watch people thrown down... and because my players were a bit confused that something powerful enough to hurl you through the room never knocks you from your feet - so it's one of these "verisimilitude" things.
Hope these explains the reason for the rules a bit!
Cheers, LT.