I think you're missing my point about R2. R2's value can be a fixed, set value because the value of the cards he's "protecting" has limits that are, generally, within a reasonable range of each other. The cheapest card he can protect is 22 points (including his own), and the most expensive ship he can protect is worth 41 points (Wedge + R2 + Torpedoes + a 4-point Elite Tactics). Luke is one point cheaper than Wedge, so adding additional upgrade options to Luke just sends that higher. If a Force Power is valued at 4 or 5 points, now you can load half your points into one ship, and R2 can defend half your fleet, or barely a fifth of it. And that's just too big a range to put a fair price on R2 that doesn't make him way too expensive to pair with, say, Biggs or a Y-Wing pilot.
I see your point but think your example proves that this is no different to the example which already exists in the game, which you gave!
R2 currently costs the same defending a 22 point ship as defending a 41 point ship! so right now he can be defending 2/9 of your squad or 5/12 of your squad for the same cost! seems like a pretty big difference to me! (almost double!) If this is not a problem currently, then making it a very slightly larger gap shouldnt be either! your concept of an acceptable range is merely a subjective and non backed up statement. you might as well be arguing that the current difference is too big, but that were the most expensive ship 3 points cheaper, this would be acceptable…
what are you basing your logic on? what tolerance is acceptable and why? your argument seems to preclude the concern that it is already a problem, surely?