More Units = Varied Matches = Better E-Sports

Suggestion:

Each Race should have 2 Units for every Technology Tier and Combat Role. i.e. There should be 2 "Trees" for each race.

• They should have the same prerequisites (i.e. the structures needed,) the same role (ground-to-air, or air-to-ground, or support, etc.) and cost the same ratio of resources (i.e. 1:0 Minerals:Gas or 2:0.5 and so on)
  
• The only difference between them should be the statistics (attack, armor, speed etc.) and any special abilities.
  

Example:

• When you build a Barracks, you will have that obvious option of recruiting Marines, but there'll also be a different ground-to-ground/air ranged unit, costing 75 minerals. Let's name them Strikers.
  They'll be slightly faster than Marines, but have a shorter range of slower ground-to-ground attacks ("Personnel Handgun") OR an even slower but long-ranged G-G/A attack ("Sniping Rifle") and the damages they both do would be roughly the same.
  
  Now I'm not asking that there be such a unit, but this's just for a rough idea of an alternative unit.
  
  
• Similarly, for the Protoss, simply constructing a Gateway would let you call, say, Martyrs in addition to the Zealots; ground-to-ground melee attackers that die (when killed, not at will lol) in a small explosion of splash damage, and cost 150 minerals.
  
  
• They'll all be distinct units in their own right; Abilities researched for one will not affect its alternative.
  

Rationale:

At very high-levels of skill, i.e. the "pro scene" there is precious little variation in overal strategies or build-orders. It tends to boil down to who can click and hotkey faster, becoming like some real-time version of Chess what with all those identical openings and their responses, on symmetrical maps.. >_>
I know this may be an over-simplification begging for flames, but you get the idea; it can be Dull as Damn to watch, pretty quickly.

Let there be some redundancy in the portfolio of units for each race. Let units overlap!

Okay, in Heart of the Swarm if not in time for Wings of Liberty, but stop worrying about issues like not allowing 2 units to share the same damage type (i.e. Splash, which the Siege Tank and a cancelled Battlecruiser ability used to have)