I just think that this kind of technology is really at its infancy. It's like drum sampling. Back in the days the snare was just note, recorded at a certain velocity/strenght and then dropped/raised in volume. Look at where we are now.
Infancy? The *maths* have existed for quite some time (early 20th century?). *Practical* applications in regard to musical application/use are more recent; I believe Sony was one of the first with an *affordable* rack unit (circa $5k US I think??? originally, released.. '99?). Soonish after, IR capable plug-ins popped up. Acoustic Mirror was my first experience (circa.. late 2000?), and I was in on early testing of Waves offering (I was VERY vocal/involved). The science is solid, and as processing ability/capability increases, we are afforded *better* operational benefit. However, please do not take that to mean that what we have now as being.. lacking. I am quite sure Cliff (and other math/engineer types, especially?) would provide deeper explanations and examples.
The comparison to the drum samples thing might actually be appropriate, but only glancingly IMO. Early sample based drum offerings (Drumkit From Hell being the *first* truly successful offering, circa 2001/2002?) had limited numbers of samples due to processing limitations, which is/was intrinsically linked with software *capabilities*. As processing power/capability increased (affordable), so software capabilities followed. DFH, in fact, had multi-samples for each kit piece. Though the product was 2 CD-ROMs, one only contained recorded pieces. The similarity? Software capability had to coincide with hardware capability. Currently, hardware capability allows for current "in use" technologies to be developed (nearly) as far as those technologies allow. Consider: would a rack of servers provide for a *better* sounding AxeFx using the current "software technologies" already in use? Or will new science/maths and thus new software be required? Is it more a matter of refinement (algorithms, programming, etc)?
As far as "why sweeps": The reading material is readily available.
Why use a "full range" sweep for a guitar speaker? It comes down to math I believe. Above 20k is another debate entirely, and that table is long worn, and likely to have some blood stains, lol. As far as "static" versus "reactive," this would be pure speculation on anyone's part, save Cliff (or anyone he has related his design theories with). I guess we could compare this, once again, with those drum sample libraries, in that each *bit* (punny? lol) is more akin to photo than motion picture, which, to carry the comparative further, when compared with "live" would be.. "missing that something." Could modeling technologies be integrated to account for this? Are solely IR/convolution based technologies too static for something so dynamic? On the latter, of course. An acoustic space will not have *reactive variance(s)* that are necessary to consider, therefor allowing the *static* nature of convolution/IR technologies to provide quite well. One could theorize that... say, combine three technologies: one, IR capture; two, an adequate number of varied, dynamically representative IR captures to properly represent the character of a time/source dynamic/timber variant (speaker), similar to the mega-layer + velocity piano/drum/etc libraries; three, modeling technology, evolved (incorporate those "IR samples," plus a "variable predictive variance and connectivity" aspect) , so as to incorporate the other two technologies, and thus provide the *missing analog* (analog here as comparative (sic), not electronic component, per se). IOW, modeling is missing.. something, and sampling can provide it, to some degree, and vice versa for sampling. Interestingly, Digidesign's "Velvet" utilizes these technologies (to a certain extent). I am unable to elaborate, but suffice it to say that my very first exposure to this was.. well appreciated.
Summarizing: I believe Cliff is working toward the same goal we all wish for. I tried an Axe Ultra, and found it lacking in such a (vitally) minute amount that given a choice between "stable of amps + cabs" and it, I had to (very grudgingly) let the Axe go. Axe Fx II, however, clearly... VERY clearly.. demonstrates the impact of improved hardware technology, a very solid foundation (Axe Stand., Ultra + incredible user base), and time spent on refinements. Cliff has explained (some?) of the major advances in regard to the IR + modeling technologies being utilized. Will the next step be one similar to what I described (ir + ir "layers+layered velocities" + incorporative, variable predictive modeling")? Or will it be something we are not aware of currently? IMO, it is close enough for many. For some, using a power amp + cab + mic is still preferred. EMWV (everyone's milage will vary.. to some extent
).
I could be spilling effluvia via my backside though...