@eXo - yes, perhaps "intended for" was not the right way to put it when making an analogy to DOS games. As you point out, unlike MAME games, the games produced for DOS were not intended for any particular machine but for a range of PC compatibles. I would however rephrase and say that shaders can be helpful to re-create the feel of the original monitors that the games were played on - and acknowledge that this will differ between individuals. I would suspect that the majority of DOS games were played on CRT type monitors rather than flatscreens. For you, as you say, scan lines and screen curvature were something to work around. For me, trying to eliminate these was never on my radar and I just enjoyed the games as they were on (originally) my parents' Amstrad 1512.
Thankfully, we both sensibly agree that this should be an option to enhance the current experience - though you say that in relation to eXoDOS this becomes tricky. I take it that you are therefore not aware of any other possibilities here within the realm of emulation, other than using a different version of DOSBOX which does support this feature?
PS - I have indeed considered getting hold of an old monitor like the above. I have not taken the plunge largely due to space and aesthetic issues though maybe one day!