I'm not here to say that anyone is wrong about the X/300 info on the calibrate screen, but if you hadn't ever calibrated anything you could easily jus passively accumulate a bunch, not really learning about how to use them strategically and not knowing that it is use them or lose them.
When you get them there is no indication that there is a maximum, so if you're the kind of person who thinks the game is a bit overwhelming with so many gear pieces and mats and currencies etc. and you're trying to focus on getting better at one part of the game, it would be **very easy** to hit the max and then lose a lot of these.
I'm not complaining, and I'm not intending to join the OP in the complaint. But I know a lot of people who play some parts of the game seriously and some parts casually. If you don't mess with mods much because mods are like paperwork and they're more PITA than fun to you, the mods are going to be one of those parts you play casually.
Those players do deserve a better warning system.
Frankly, I also think that there should be a better warning system when maxing out Datacron credits.
It wouldn't be hard. Just every time you would have gotten one but it is not added to your stash because you are maxed out, the game should display the number you would have gotten and a message saying, "The game declined to give you X credits/attenuators/whatever because you have reached your storage limit for that item".
I suppose there would need to be a setting turned on by default but that you could turn off if you really, really don't want to mess with them even though you know there's a maximum. Otherwise the messages would get annoying quickly.
But overall, I think that it's a reasonable design choice to set a max (even a relatively low max like 300 attenuators) while I also sympathize with people who want warnings.
I don't think that's too much to ask.