Why does Garmin not allow to install Montana 7X0(i) preloaded CN maps locally for BaseCamp?

Garmin-Andrew will have to answer that question.

Very disappointing indeed!  Not in keeping with the claim on the recent press release here:

"Dedicated to helping people make the most of the time they spend pursuing their passions, Garmin believes every day is an opportunity to innovate and a chance to beat yesterday. "  

Copy your Garmin folder to a USB drive and plug that in when you are using BaseCamp.....

Sure, the workaround with the virtual disk will work. But it's not elegant as the option to install CN maps for BaseCamp directly. I really don't understand Garmin, why the don't want to provide the option on 700i / 750i series.

Contact support. The more people who report the issue, the more likely it is to be addressed.

There is no 'Issue' to report - the Garmin Engineers already responded that this was intentional and by design.

Well, they still forwarded, that I have the wish to enable the possibility. Who knows, maybe they rethink, if more people complain.

I'd still call. This would not be the first time a support rep was misinformed (or just took the easy way out). That said, I wouldn't hold my breath waiting for a change ;)

It seems, that I have found some sort of a reproducible workaround,

with makes it possible to install CN maps via Garmin Express on computer with Montana 700i/750i.

To make this work, you you need to setup your Montana to 'Garmin Spanner' mode (Setup -> System -> Advanced Setup -> Interface).
1) Start Garmin Express and choose your Montana
2) Connect Montana via USB
3) When Montana asks, if you want to enable Mass Transfer Mode, don't do anything. Just let is stuck on this question.
4) Wait a few seconds and Garmin Express will say, your Montana is connected, but the new map management feature is disabled in Garmin Express.
5) You can now install the usual way the preinstalled CN maps via Garmin Express on your computer.