I don't recall anyone suggesting Parthiv or Vaas would open. That would be a strange decision.
To the extent that Irfan Pathan bats at seven, where he is unlikely to have much effect, when Karan Goel opens in that Punjab team listed above? I'm not getting at the 'open with specialists' argument as much as the 'leave world class batsmen at numbers five, six and seven' argument. You don't seem to recognise that Shaun Pollock could easily bat in the top order for many Ranji sides. The gulf in class is enormous.
There are some folks at different places, even here, who think Parthiv should open for Chennai. He's hardly world class. Opening with him is no different from opening with Vaas, though that's never been suggested.
With the kind of squads picked, you have openers picked locally, while the world class batsmen are predominantly in the middle-order. There are, of course, teams like Kolkata (this team will be in a really tight spot), Delhi and Mumbai, who have four openers, Indian and international. These world class batsmen, of course, can bat anywhere in the order, especially when in good form. We don't (at least I don't) expect the local openers or middle-order batsmen to fare too well outside of their specialist positions. Putting these two together, this will get a lot more out of the batting rather than push openers down. In most teams, the limitation is due to the composition of squads.
Pathan isn't an opener, and not quite someone who'll get you a century, or a fifty an innings. He's more a 24-off-13 hitter, more useful at that position. He'll add some shock value and power play at the top (like Gilchrist and Sanath), but it's a risky proposition. Karan Goel, though, has opened more than a few times. Pollock may make a few Ranji top orders, but those are Tier II teams that struggle to play out draws- far from teams from Mumbai, Delhi and Karnataka. We don't anyway expect him to do much against a world-class pace attack as opener, and that (Mumbai) team's bottom four isn't very strong- they also have Sanath and Sachin opening.
Looking at the scene, team by team-
- Chennai- Competent opener Mukund, not too great Aniruddha, weak middle-order options among locals, bar Badrinath.
- Hyderabad- Keeping in mind the foreign cap, we need at least three Indians in the top six. One is the competent Ravi Teja, then there's Venugopal, then promising young Rohit Sharma and finally, Shivlal Yadav Jr. One of them's an opener, and one's just not good enough.
- Bangalore- Cameron is a good choice, so is Praveen, and there's the established Jaffer. Slightly tricky scene there, but the rest bat in the middle.
- Kolkata- Ganguly and Gayle open, or else Chopra comes in. Tough scene, as we've already noticed.
- Mohali- Nice. No openers, bar Sangakkara and Goel, also Kaul, all non-regulars.
- Jaipur- Yusuf Pathan and Graeme Smith open, easily. Langer misses out due to the foreign limit.
- Delhi- Four openers. Top picks are Sehwag and Gambhir. Dhawan may bat lower down, and that other opener may not get a game.
- Mumbai- Easy- Sanath and Sachin.