Well...in order to use the transmute spell, you have to have an adept level at alteration, yes? Not every CHARACTER would know that or would want that. Again, we are falling victim to player knowledge, not character knowledge.
No, you can use it as soon as you get your hands on that book. And it's easy/natural access because it's located in a rich ore mine that's very close to Whiterun.
Your second point- of course a character would want to increase their talent. But rationally, the CHARACTER would expect to do that by crafting more complex items. As people have pointed out here several times already, how does crafting 300 iron daggers make you a master smith? Your character wouldn't know that. You do.
Ermm it's not really that one sided. A very well made dagger can take much greater skill than some ordinary armor. That's why you see a simple steel swords going up to $5000 because of their craftmanship (pretty well made full plate goes around $2k ~ $3k). Making nothing but iron dagger is obviously counter intuitive idea to learn more, but only going after the most complex armor then throwing away all materials is just as counter intuitive.
I'm thinking about this and I think it would have made a lot more sense if blacksmith perk tree was divided into weapons and armors, or into two completely different perk trees as weapon smithing and armor smithing.
As far as playstyle goes, again, it goes back to how TES games have always been- the playstyle is incredibly open, so that people CAN powerlevel if they choose to. If you don't want to, you need to roleplay. It's not as difficult as people like to believe. And I appreciate a game that treats me like an advlt instead of smacking my hand and telling me I can't have cookies for breakfast if I want to

I just want to point out that this is rather weird you are quoting me on this outside of the context of the message I was replying to, because it's very context sensitive.
Within the context, my point was that it takes a very particular playstyle to stay low level and weak. Almost any attempt to make a character who is skillful in combat is going to trivialize the combat. So in order to successfully roleplay and stay weak, you essentially end up roleplaying a weakling, which is particularly narrow style of roleplaying in a game where you are suppose to be THE dragonborn.