I appreciate the opportunity to think on the subject of whether conditional move history would help me. I play 20 correspondence games at once, and I enter conditional moves almost every time I place a stone (believe it or not).
I have thought about it for fifteen minutes. Conditional moves notification/history would not help my style of using OGS. I already, every time I return to a game, click backwards ten moves or so and watch those moves again so that I understand the flow of the game again, recall tenukis (so I don’t forget about some other “hot spot” on the board), and remember my strategy. Using the ten move click back button, then clicking through takes me all of three seconds (okay, maybe five). If I had a notification that “three of your conditional moves were used”, I would still click back to review them. So, for me only, there is no advantage.