To put it in your format, my argument is:
1) There exist many interesting decks that do not have the option to compete with Dim Shield in its current form.
2) Nerfing/Eliminating dim shield would allow those decks to compete.
3) More interesting competitive decks is good.
4) Therefor Eliminating/nerfing dim shield would be good (independent of any other proposed solution that might also be good).
I take issue with your oversimplification of step 2.
2*) Nerfing/Eliminating dim shield
or altering those decks would allow those decks to compete.
This has a cascading effect of
4) Therefor Eliminating/nerfing dim shield
or altering those decks would be good (independent of any other proposed solution that might also be good).
5) Since more decks is good, the change that results in the most decks is better. [Adding X decks by removing Y decks is worse than merely adding X decks]
6) Therefore we should be biased towards strengthening the decks that cannot compete rather than weakening existing decks.
@Vangelios
You are overestimating the significance of infinite DR with finite duration. I have not seen you claim Sundial is OP. Since you do not consider Sundial OP, then the existence of infinite DR is not the problem.