There are many many reasons to leave the superdrive out, and only a couple to have it in.
Having repaired many Superdrives, they are rather complex, several moving parts, loader, laser assy and screw-rail
Superdrive
Often is the case that the laser lens gets dirty, and no easy way to clean it since its a slot loader.
Fewer the parts, the more reliable, as such the Macbook is better off logically without an internal Superdrive.
The sensible option is to remove the HIGH failure point from the Macbook,..... being the Superdrive and make it external....so in case the superdrive has an issue, you dont need to service the entire Macbook. This is logical, this is sensible, this is best for the consumer.
Since I probably burn more DVD blanks (data archives and distributions of same) than everyone in this thread collectively most likely, ....burning around 300 DVD a month with 3 replicators 1 x 8 towers I know the value of DVDs
I currently have 4000+ JVC Taiyo Yuden blanks awaiting future burning.
However most consumer and Prosumer DVD use is data archiving or commercial production for limited use (weddings, archival footage, archiving vital data).
People who dont realize that while DVDs are extremely vital for this limited market (as I mention 4 or 5 pages ago) , the 95% bulk of overall DVD use has gone online.
or as meant 80% of commercial Audio / Video / Software
Such a disconnect on the part of some to realize this fact is just a lack of research.
The main use and currently only "developing" (expanding) market for single/dual layer DVD use is for data archiving important media
https://discussions.apple.com/docs/DOC-6031
DVD professional archival media
Drawbacks:
1. DVD single-layer disks are limited to 4.7Gigabytes of data.
2. DVD media are, given rough handling, prone to scratches and light-degradation if not stored correctly.
Advantages:
1. Archival DVD professional blank media is rated for in excess of 100+ years.
2. DVD is not subject to mechanical breakdown.
3. DVD archival media is not subject to ferromagnetic degradation.
4. DVD archival media correctly sleeved and stored is currently a supreme storage method of archiving vital data.
5. DVD media is once written and therefore free of data corruption if the write is correct.
6. DVD media is the perfect ideal for “freezing” and isolating old copies of data for reference in case newer generations of data become corrupted and an older copy is needed to revert to.
7. Best-idealized 4th platform redundancy for data protection.
8. *Level-3 (highest) security of your vital data.
The point, due to lack of investigation on some peoples part, that you have missed entirely, is that the Superdrive is a slot loading drive........
1. meaning cleaning the laser diode lens is impossible for the common user, .....however this is not a mechanical failure ,but nevertheless cannot be cleaned by users.
2. Additionally, having burned more blank DVD than anyone youll meet, I can tell you that users have / do/ will complain that a DVD burner is defective when in fact its the huge amount of low grade BLANK MEDIA that is at issue. low grade DVD blanks have about a 8 to 10% reject rate.
3. Also the slot loader has several MORE moving parts than a tray loading DVD player / burner.
4. All these collective facts combined with , now, very low need / use of DVD for commercial media Audio / Video / Software, is the premise for the removal of the DVD Superdrive from the Macbook
5. Additionally it could not fit in the slim Macbook(newer) chassis.
6. also externally now, the Superdrive doesnt require the Macbook be serviced, rather only the Superdrive, ....very logical.