Yeah, yeah, sure. It's so "natural" to see if you killed the target or not - only on the next turn.... You know what? You should also make the same "very Piriate style" rule not only for grenades, but for the bullets too.
And you should refrain from trolling. Since I assume you're intelligent enough to not spew such gibberish while being serious about it.
Edit:
Following answer is adressed not to the poster (since from my years of experience, trying sane dialogue in such situation never works) but to explain the issue to everyone else. A little history first: instant grenades was a later modification of the vanilla game. A modification that was hilariously OP in vanilla (esp. regarding smoke grenades), but that's not even the major point; it can still work in a mod built around it, and it was maybe interesting in pre-OXC days, where adding NEW weapons or minute-modification of existing ones was very hard.
The point is, that since from the start I had superior OXC tools to add as many weapons as I wished, I found full conversion to instant grenades as an uninteresting avenue of modifying the base game, since it's eliminating some of the tactical variety, giving nothing in return (the arcing, instant explosion effect can be produced in different ways, without the need to cut off the option of delayed effect). And last I checked, all OXC built-in mods to XCOM mechanics are voluntary, not compulsory.
Then, a (largely needless) mental experiment:
1. Assume we made all grenades instant.
2. This leads to immediate and major increase of their power, while limiting tactical options (like drop n' run).
3. The latter is a permanent loss, but the former still needs to be adressed.
4. This would be adressed with nerfs to their power and/or accuracy and/or speed.
5. Resulting in tactical options being even more curtailed, not to mean several types of grenades would be superflous to already-existing instant explosives.
6. Alternatively, if step 4) is not taken, it would boil down to classical "louder, bigger, faster, dumber".
