Should Macs still have DVD drives?

Is there still a reason for Apple to provide DVD drives in Macs and MacBooks?
The four main reasons for the existence of a DVD drive are:

1. Install the operating system. For that, Apple now includes a 8GB minimalistic USB drive with its DVD-less machines (i.e., the MacBook Airs).
2. Install programs. For that, there have always been downloads, but now there additionally is the Mac App Store.
3. Watch videos. Still a very valid reason, but Apple would rather see you use iTunes to download videos. With Apple not supporting Blu-Ray, things have long looked a bit silly in this area for Macs, anyway.
4. Data storage. For most purposes, USB drives (and possibly Thunderbolt drives) are enough. Again, without Blu-Ray, there is less of a point to support this. It would be nice to have more compact storage media, anyway (credit-card-shaped? hologram-based?).

With all of these reasons gone, why would Apple build a DVD drive into their next machines? But what would then set the MacBook apart from the MacBook Air? Only faster processors and non-SD hard drives?

Not having a Blu-Ray option hurts Mac users, but with Thunderbolt, there is now a way to both drop built-in DVD drives and still support Blu-Ray in an elegant way. And without making standard Macs more expensive.

• Provide an external Thunderbolt-based Blu-Ray drive. Then users can decide on their own whether they want Blu-Ray or not. Apple can charge extra, should it feel that licensing costs are high. But do provide it, Apple! Thunderbolt carries enough electricity so that such a drive would not need a power supply.
• Support Blu-Ray playing via a Mac OS X app. Only deliver it with the drive, if licensing costs are an issue.

Not supporting Blu-Ray is another case of a strategy tax: Considerations of one department (iTunes movie store) lead to decisions that are negative for other departments (Macs).

Related posts:

1. More Mac app store news: user experience, prices, etc.
2. Thunderbolt (code-named Light Peak): an overview
3. John Siracusa on the Apple strategy tax
4. Bag of hurt [Marco Arment on how user-unfriendly Blu-Ray is]