Yes, I definitely agree, whatever time is to blind enemy players, is far too small, I mean the opening window is great and all, but without a slowing or stun effect, the flash by itself, is little more than an annoyance, than an actual opening act.
This is generally due to the intended effect of “disorienting” your enemies, work’s amazingly well in PvE, especially against thralls, but falls short on Battleborn’s. The reason being, is that the instinct’s of most player’s is to immediately go backward’s, which is, extremely easy, I mean, during beta’s, Caldarius was a toughy, but when he flash bangs me, I generally had a team to back me up, and more over, probably get him while he’s over extending for the kill.
That 1 second blind, is just too short and if anything, is meant for character’s like Phoebe and Thorn, to get in their attack’s. But using flash bang and then gravitic burst in tandem to get behind the enemy, has worked wonder’s for me too, but the opening for it is very short, in fact so short, I have to activate it as soon as I press it twice, and then activate gravitic burst which, while it does work well, it force’s me to over extend a bit myself since I sometimes miss the initial hit, and go further than intended.
So I do agree with the OP, in giving him 0.5 seconds extra on the flash bang, anything greater will be too much.