Towers: How do we make them more interactive and not just a useless chess piece?

We've all been concerned about the poor damage and defenses of our friendly neighborhood towers.

I didn't generate too much thought behind it, but why can't the power/defense of towers be managed by the following: note not all of these have to take place at one time.

1.) The amount of champions still 'alive'. -- By this I mean; for every champion still 'alive' on your team, your towers gain X more damage and X more defense.

2.) Towers gain more defense depending on how many champions are nearby. Towers's defenses are unaffected by minions nearby who do NOT have a siege minion with them. -- This can be elaborated as such:

a) If there are no champions nearby and no siege minions nearby, the towers defense is reduced slightly. b) if there are champions nearby but no siege minions nearby, the towers defense is affected by how many champions are nearby. c) If there are no champions nearby and there is a siege minion nearby, the towers defenses are drastically reduced (to the same standard they are, which I believe is... 0?)

3.) Turrets gain Health over the course of the match, but lose defenses over the same amount of time. The defenses are still affected by the above rules.

4.) Turrets now have an additional upgrade after the first 10 minutes of the game: (only one upgrade can be chosen for each tower. Each upgrade will be active on the turret for a minimum of 5 minutes before it can be changed. The first upgrade is free, but any changes to that towers upgrade thereafter costs an X amount of gold.) a) Better response to enemy attacks. (Turrets will target enemy champions a lot easier/quicker than standard.)
b) Turrets have increased sight and attack range.
c) Champions hit by consecutive Tower shots will have their movement slowed and are revealed for 2 seconds after leaving the turret's range. d) Turret gains a searchlight ability. A nearby friendly champion may activate this skill by standing close to the turret and choosing a path in which the search light will travel for a duration of X seconds every x times and has a cool down of x seconds.

5). Turrets now deal true damage. The damage is the same at all points in the game. After the first 10 minutes of the game, turrets shots will decrease the targets armor/magic resist by x% each consecutive shot. Stacks fall off after x seconds of not being hit by a turret shot.

6.) ??? I ran out of ideas at this point since I now have to leave work.

Penny for your thoughts??