[thejeff]

Of course by that argument, having PD at all eliminates the viability of certain force levels, levels 1-3, thus limiting strategic options.
Therefore PD should be removed from the game. Anyone who doesn't agree just wants the game to be simpler and easier so that they don't suck as hard.

One could also argue that PD is itself a strategic option and thus increases the the diversity and complexity of the game. Making it more viable would then add to to your options. You would have to choose between building static defenses and mobile forces rather than just putting a point into PD to stop scouts and investing everything else in "mobile forces"

Or to put it even more simply, mobile forces are not the only thing that gives rise to strategic options. Static defenses, represented in this game by forts and PD, can also increase your strategic options.