The problem is that that way tends to end any games far before the later eras.
If we want to fight the "Three mods" issue, then the challenge needs to be kept up. And one solution is to make it hard to run away too far by giving you a penalty if you are too far ahead (or any of the AIs is too far ahead). This means you can still get ahead but the further ahead the harder it gets unlike now when it actually gets easier and easier when you have a headstart.
That's what my new EraInfos changes will do, currently it does this to a certain extent, but after Friday if you are in a later era your research rate will be much more noticably slower, especially from Classical to Medieval and Medieval to Renaissance. The other thing I'd like to see done is for Tech Diffusion to be tweaked to give more significant benefits to under-teched civs neighboring leading civs.