I think you're really underselling just how big of an advantage that the spires would give early. And I don't see the idea of skarner being significantly weaker off of spires to be a good thing. That is the #1 complaint people have about him right now.
I don't like the idea of simply being "outstatted" from level 1 onwards. The only true way to avoid that is of your team snowballs and you stop skarner from getting any of his own spires. That would feel absolutely dreadful. Who is that fun for? It's not exactly fun for the enemy team to be constantly worried about extra objectives because their enemy pick Skarner. And it isn't exactly fun for his own team because it is a benefit that just kind of happens for most of the game.
To be blunt, Skarner might bring a bigger emphasis on map awareness like you want, but I don't think it would be in a healthy way for the game. Anyone who doesn't have map awareness won't suddenly have it because of this idea.
Currently about the vision idea with the spires, this currently already happens in high elos. If I see the soires change over, assuming we're in a good position to do so, I will collapse on him. The suggested change doesn't further emphasize this, it just makes those pillars stronger for his entire team if you can't contest them for whatever reason.
Let's say we go with the suggested 1% health / mana regen as an example. Lets say I'm an adc at level 1 with 500 health for simplicity's sake (much lower than the average health pool level 1). 1% is 5 health every 5 seconds, which doesn't sound too bad. Over the course of a minute that will be 60 health over the course of a minute. That's nothing to scoff at, especially since this is realistically less than what you will actually get as your health pool will be higher. Factor in life steal and that this only gets stronger as the game goes on, that is insane. You'd be hard pressed to actually force that adc out of lane through any kind of trading unless you can do an all in.
Same goes for the mana regen. Mana amounts are going to vary a lot more between champions, but let's go with 400 (so average amount for a mage give or take). That 4 mana every 5 seconds, which equals 48 mana per minute starting from level one. Not counting other forms of mana regen, that already gives them a lot more staying power in lane since it is rare they will be casting spells off CD and can either have more mana because of
(which means more mana regen from spires) or a lot more mana regen thanks to doran's ring.
This is all starting from level 1 with simplified numbers to show that this is actually incredibly strong. If I'm on a team with Skarner, chances are I will automatically win any trade because I simply have more regen. That feels terrible in a pvp game. You weren't out played, out matched, etc. You were out statted. Riot has been moving away from things like that. WW is getting a rework finally, Urgot has been kept in the dumps for awhile, taric was reworked because he just gave free stats, etc. And that's exactly what this change will do, but in a way that not only feels bad for the enemy, but feels bad for the skarner player while going unappreciated by his team mates.