i don't know whatall makes these things go up and down, but i'd sure bet it has more to do with the AVID video editing system losing market share to Final Cut Pro, rather than anything to do with Pro Tools. it is INSANE how many legal and illegal copies of FInal Cut are out there. only the high end places have AVID's here. and they MUST have at least one FCP edit bay. they lose business to the producer or freelance editor who can install FCP on their mac and charge less $$....
look at the films that are being touted as 'Edited in FCP'. i just gave a seminar on sound for a film that i did using Apple products...the regional 'Pro Film & Video' sales rep from Apple was there and he was very aggressive about talking about their produts and pushing Soundtrack Pro (ha, ha!) and Final Cut....he also talked about how big FCP is becoming and they are puting a lot of marketing $$ into letting people know you can get 'A Big Hollywood Look' with off-the-shelf products from Apple.
i also know from talking to Product Managers at DIGI (who speak rather candidly to me) that they sure as shit watch their competition very closely. they have operating copies of Nuendo, Logic, Cubase, Pyramix, SAW studio etc... in house. not saying that they can't improve jus' saying i think it is a mistake to think this has that much to do with pro tools.
as to bashers, there sure as shit a bunch of them... i don't use Nuendo, but i don't BASH people for using it or the product itself. it has some cools features. in fact, you can go onto the Nuendo Forum and see people saying that people are lazy and stupid for using Pro Tools.... even though they are, i am sure, the exception, they are very vocal. as a (small) studio owner, i look at everything that is available to me and make a decision based on what i can aford and i think i will need. all the DAW's have something to offer.