Garmin's reason for C: drive only
Garmin is going to be implementing a more automated map updating process. They need to know where the data is on your machine to facilitate the update. So it's not going away in the future. That's what the garmin software person told me.
I understand why they are doing it because it greatly simplifies the updating process. I still think it sucks. If there's enough public outrage they may be forced to change this.
I'm tired of waiting on the phone with Garmin. I have over 5.5 hours of hold time this week. I have talked to multiple people at Garmin and I'm still waiting for someone to enter a correct registration date for my most recent GPS.
It doesn't look like Lowrance is going to provide much competition. They only have two automotive offerings on their web site now, the XOG and the Baja.