The second reason is that if something breaks, you end up scrounging all around the country to find a replacement part. So your radio system can go belly up until a replacement part is found.
I sure would not like to be in the position of having a radio system that is on it's last legs and not have a fall back to use if it does go down. This is the main reason that users still using EDACS are basically on life support of the system now.
How would you like to be using a radio system in this position? Then consider that even if the agency can scrape up the big money for a new radio system, it is going to take about 1 to 2 years before the new system can be on the air. This is a long time to gamble on the people out in the field that rely on a working radio system every hour they are using it.
As someone who was hired to support and manage a 31 year old Smartnet II system, one of the first analog simulcast 800MHz systems in the US, and dealing with DAILY failures of MSF5000's with age related problems like crystal whiskers growing on the VCO cans causing static on receive, an Astro TAC comparator that took up a wall at our prime site and would have fits, good ol' Ball Ephratom rubidium master clocks, monthly "mod comps" to get audio levels balanced between sites, random bouts of failsoft thrown in here and there due to a site controller that had cronic electrical flatulence...
All that said, sure, I MISS the sound of our old Smarnet analog- WHEN IT WORKED, IT WORKED WELL. Keeping a 31 year old, tired, long unsupported and on the verge of collapse system like that alive any longer was playing a dangerous game. People's lives depend on this. It's not to provide "hi-fi" audio to consumers on scanners. It's to provide a lifeline that's always available for those who need it to work.
We're 5 years into our P25 system and two and a half weeks from a major upgrade of core components. I'm excited and nervous but I also know the vendor has it, and they've done three other upgrades of P25 systems in my area over the last two months. We're getting current servers, networking hardware/software, refreshes on all consoles including new PCs. All of it to give us another five and then another refresh. All of the GTR8000s are 2nd gen and I've had only ONE failure in five years of ONE power supply- easily rectified by a FRU swap. No digging through boxes of old junk parts like driving a Rambler with a "whirlpool in the tank".
"Look out over here, watch out over there, can't afford a blowout cause we haven't got a spare" aren't in our vocabulary since 12/29/2015.