No, not really. DVDs are super inconvenient for managing data.

I used to back up movies, books and games to DVDs. At the U, I managed the particle physics department pirate library. It was an actual (unpaid) job that required a huge time investment. Later, I worked with people's private data/media collections on HDs. I also have a private library of actual paper books (which are static and valuable as they are and won't be updated and aren't going anywhere) - and it's still a pain in the ass to document. So I have the experience of working with private data storage on a large enough scale to notice what works and what doesn't, and here's what the experience taught me.

- Compiling the collection to optimize disc usage, removing trash files, writing and then checking the disc, labeling it and saving metadata eats up time like you wouldn't believe. Then, eventually, you're going to fuck up and/or your collection will require updating. You'll discover the metadata/labeling scheme you initially developed cannot handle updates.

- With 4.5GB to a DVD (kinda), you'll probably be able to fit 4 actual GB on a single disc on average. A HD holds upwards of 1TB and costs roughly 2/3 of what DVDs cost (per byte, 100pcs spindle). But with DVDs, you aren't going to be able to access all that data at once, because it comes in arbitrary 4GB pieces and you only have 1-2 DVD drives. Let this sink in: to access all the data I have at my fingertips with a cheapass HD I bought in 2010, you'll need 350 DVD drives. 350. Of course, you aren't going to actually need ALL THE DATA provided your collection is static and your metadata scheme is perfect (false and false), but just the overwhelmingly hueg scale of that number makes it plain to see that no, the data isn't going to be magically sorted to DVDs to always be conveniently accessible.

Specifically, a collection of GOG games needs to handle:
new games
new versions of games, to replace obsolete ones
new releases of games, to complement existing releases
new versions of releases, etc......
new extras and updates to extras
mods and fanpatches
possibly some other game-related user-generated data like saves, logs, videos etc (optionally)

- What if you need to make a raw search for something unaccounted for in the metadata? On a HD, you can build an index with any software application you happen to be using at the moment. DVDs? Tough shit. DVDs are glacially slow.

- Finally, there's the matter of reusing/recycling resources. If you shell out for a dock/enclosure right now, you can always stick these HDs into a desktop or a NAS later. DVDs are useless. And don't even get me started on rewritable DVDs - you aren't going to rewrite them if you value your money, because burning a new DVD is cheaper than messing around with the old one.