A bit irrelevant since most large installs are for pro-oriented software that cost half as much as the entry-level MacBook itself. That being, if you are a "pro" and use pro-level software then you'll have other ways to install software like from an external optical drive or from a shared distribution point at work or at the home office (like via a LAN or a remotely mounted optical drive). You say you don't want to be bothered by carrying around an external drive? I say, how many times have you had to install a mega-megabyte program from a CD/DVD while riding the train/subway, etc. to or from some destination (or under any situation while being completely mobile)?
The only widespread problem I can see for large installs would be for games, but then again serious gamers aren't going to balk at getting an external optical drive. However, if they could forgo the optical drive and get another hour of gaming while running on a larger battery then I think they'd make that compromise.
There could also be a pretty big, but admittedly self-serving incentive for Apple to remove optical drives from their computers, since that would nearly guarantee a monster success for the Mac App Store. The more quickly and completely software moves to online distribution the faster Apple will make their 30% cut from potentially all or nearly all software sales. I'm not trying to be conspiratorial (i.e. bad and greedy Apple), but that could represent a win, win, win for Apple, their customers, and even for many software developers (as for the latter, just look at what happened to Pixelmator).
Lastly, if you think large installs over the internet are going to be problem then why are so many in the industry rushing to streaming video delivery rather than relying on DVDs/Blu-rays? Apple has been pretty adamant about that and even NetFlix is saying that internet-based content delivery is the future (and they are currently the largest distributor of DVDs in the U.S.). It's practically the same argument, the cost savings and convenience of internet-based delivery are just too great to continue with physical discs and packaging.
I could say the same thing about your arguments as to why Apple needs to keep building notebook computers with internal optical drives. You seem to be pretty close to making an out of hand dismissal of my point of view.
Okay, so you dismiss my argument that the 13" MacBook Pro could gain a more powerful GPU by dropping the optical drive and then you turn around in the very next paragraph and tell someone else that they should just "suck it up" and get a Core 2 Duo because any re-design of the 13" MacBook Pro would have to be limited to the Sandy Bridge's IGP. You seem to be trying to find every excuse possible to keep the MacBooks in their current configurations, hardware that sounds awfully like any generic PC (or worse) that you'd find at a discount electronic store. I believe that you mentioned earlier that you work with customers to determine what they should buy, you don't happen to work at Best Buy? Okay, so that's a pretty low blow and an unfair stereotype, I apologize.
In any case, it's my opinion that the optical drive is going away fairly soon. If it doesn't happen this year on the redesigned MacBook Pros then it will happen in 2012. The question then becomes, how forward looking is Apple going to be and how much risk are they willing to take to make a quick and clean break with the past and move on to what I (or they) believe is a better or more balanced solution for the majority of their customers? I think the MacBook Airs (which Apple has already said represent the future of MacBooks) and the recently opened Mac App Store indicate that this change may be closer than many might think. Would I be devastated if the newly redesigned MacBook Pros keep their optical drives? No, not in any way, and I'd admit that internal optical drives might stay for another year. However, if Apple can drop the optical drive from the 13" MacBook Pro and use that space for the additional features that I've previously proposed then I'd be jumping for joy and literally be rushing out to buy a new MacBook Pro.
