Anyhow, it's very probable that the producers decided that after the success of Batman Begins, it was the best moment to achieve a commercial success with a proyect that they have before, becuase of the similarities with Nolan's work.
They jumped on the "reboot the franchise/origin story" during the success of Batman Begins, thus I do consider that to be trend-following.
That's not true, or at least, isn't accurate. The announcement that Bond 21 would be the adaptation of the novel Casino Royale took place in early 2005, while the premiere of Batman Begins (and hence the start of its succeses & trend) was later on june 15 of the same year.
The courts awarded Eon the rights to Casino Royale as far back as 1997, if memory serves. If not then it was 1999.
Remember the period 2003-2004? Brosnan suggesting 'paralysis' on the part of Eon and then suggesting his future as Bond was 'opaque'?
With the rights in Eon's hand and Brosnan's Bond having run it's natural course in the over-the-topness of Die Another Day, the re-boot idea and the genesis of the version of CR we got lay in that 2003-2004 period.
In fact, Daniel Craig was approached as far back as 2004 for James Bond and only when he got the script in his hands (with Paul Haggis' name attached to it) did he remotely budge.
Batman Begins had nothing to do with the 'origins' story in the Bondverse. I remember everyone and their grandfather doing 'origins' at that time, begining with Darth Vader/Star Wars prequels and then later, and less successfully so, Jack Ryan (The Sum Of All Fears) and Exorcist The Beginning, even a Hannibal Lector origin movie.
So to credit Batman Begins for bringing about Casino Royale is just plain incorrect, especially in light of the fact that Brosnan was wanting $20,000,000 for Bond 21 and Craig was going to get about $1,500,000 for it. The natural solution was to go younger/cheaper/better on the lead and use the savings to make Bond more relevant again by re-booting it and grounding it in reality with propper writing and real stuntwork. They were never going to accomplish that with a 53 year old who was pricing himself out of the market and who audiences already had pre-conceived notions about.
So, I beg to differ with respect to the suggestion that it was Batman Begins that led to Casino Royale. A lot of work and thinking went on prior to the announcement of Bond 21 being Casino Royale. You simply don't start work on a major re-boot on a franchise the massive size of James Bond only three or four odd months before shooting starts.