Seboist said:
Not only that but after the confrontation with Letho he offers Geralt nothing.... and provides nothing for the rest of the game.
Neither does Roche.
Ironically, Roche is more helpful to Geralt if you're on Iorveth's path than on Roche's path.
In theory, both can help Geralt with finding Letho, but both got caught up in their own politics.
There are several reasons why Geralt would want to side with Iorveth. The problem is not there. What could have been done is have Iorveth have one sentence about Saskia to further the ideological reason for siding with him if one seeks to be ideological.
We know about Saskia in Act 1, but a tiny bit more could have been added. Unlike Roche who is not planning to join Kaedwen, Iorveth is planning to join Upper Aedirn,so we needed more information on it.
EDIT: Yea you might say that the Order / Scoia'Tael was more important and useful in the main plot of TW1. But truth be told, even until now I am not sure why the Order and the Scoia'Tael would even fight Salamandra for Geralt, especially the Scoia'Tael. To me it seems just to be a favor for a favor, but we are talking about risking dozens of soldiers.
In contrast, the Blue Stripes / Scoia'Tael of TW2 seem more real to me because they just don't follow Geralt wherever he wants and they have agendas that far supersede Geralt's. In essence, they don't really give a damn about Letho that much or Triss. Geralt only aligned with them when it seemed like Letho was a priority of theirs (which I believe it was early on), before they got caught up in a war, conflict of interests and the future of their respective nations.