Apologetics vs Criticism

Given the comments on the following quote over at Faith and Theology there is little remaining doubt that apologetics continues to be the ready target of high-brow theological discourse.  Here is the quote,

“The philosopher is not an apologist; apologetic concern, as Karl Barth (the one living theologian of unquestionable genius) has rightly insisted, is the death of serious theologizing, and I would add, equally of serious work in the philosophy of religion.”

—Donald M. MacKinnon, The Borderlands of Theology: An Inaugural Lecture (Cambridge: Cambridge UP, 1961), 28.

 I should state that I am not assuming a monolithic approach to apologetics.  I consider apologetics an attempt at stating the positive case for a held truth.  So this of course can be done in many different forms.  I think apologetics is often criticised for its reactivity and inappropriate methodology.  The methodology piece is again of course dependent on the particular expression.  My question is what the difference is between apologetics and the type of criticism entered into readily by so many of the bloggers who so roundly denounce apologetics?  Both assume that the reality of error and the possibilty of at least expressing things more truthfully (I am not thinking of things propositionally here).  I would have to say that good apologetics at least has the benefit of being courageous enough to put out substantive contributions.  I would see Halden's (Inhabitatio Dei) ongoing work around martyology and non-violence as a type of apologetic project.  I agree that we do not need to defend our faith or submit entirely to modern material-scientific methodolgy, but again I see that as a type of apologetics.
Anyway, I always start to get a little cautious when academia finds too clear a target for criticism as opposed to entering critically (and/or constructively) with particular discourses.