Not everything needs to be seen on blu ray. A lot of the films I have will never appear in this format. The picture wouldn't be improved anyway.
I think as time moves on there are fewer and fewer reasons to stick with DVDs only instead of upgrading to BDs and a few reasons for upgrading could include:-
- Disc storage space with a BD holding 5 times more info giving the disc room for better audio, video and supplements.
- BD resolution 1080p (High Definition) 1980 x 1080 pixels or 2,073,600 pixels compared to DVD resolution (Standard Definition) of 345,600 pixels meaning BD has almost 6 times the resolution of DVD.
- BDs have greater colour space allowing deeper saturation levels.and wider colour spaces.
- BD improved format features with dynamic menu system and advanced features that allow you to interact with online content
- Audio: While DVDs support Linear PCM Dolby Digital and DTS Digital Surround BDs added Dolby Digital Plus, True HD, DTS-HD etc.
- Blu-ray players can be bought really cheaply nowadays (for under 50 quid) and the prices of BDs themselves can come down to DVD prices not long after release and some discs nowadays are only getting a BD and not a DVD release.
- BDs are less prone to scratches when compared to DVDs.
- Ultra HB Blu-ray is coming with a resolution of 3,840 X 2,160 pixels and improved audio Dolby Atmos, DTS:X. etc. etc.
- You could check out some of the many screencaps of DVD and BD comparisons and the difference is very noticeable.
It's true that a Blu-ray and a well-mastered DVD can look very similar IF YOU ARE SITTING FAR ENOUGH AWAY from the TV as there is a point at which our eyes lose the ability to take in the additional detail.
It's also true that many films may not make it to BD (though never say never) especially when the studios keep on with the annoying habit of releasing and re-releasing the same damn films over and over and I'm maybe in a similar position to yourself regarding films on another format (in my case SVHS tape not DVD) that have not made it to BD during the past 10 years or so that Blu-rays have been with us and out of the over 800 classic films on tape I've been able to source maybe 10% of these on Blu-ray and then mostly Region Free copies from The States.