All companions being player-sexual means by extension that all companions are, within-game, bisexual. And everyone being bisexual is unrealistic and immersion-breaking.
If you need realism or its immersion breaking for you, I have some bad news
What is the problem you are solving? Does your proposed change solve the problem? Is your change feasible? What else will be affected by your change? Will your change impact revenue? Does your change align with the goals and strategies of the organizations (Larian, WotC)?