The major appeal of an arena in those railyards is that it would be one (albeit major) cog in what could be an explosive driver of growth and development in a large area. You get that arena built there, and all of a sudden, between Raley Field, the arena, and slowly developing downtown entertainment scene, you have a marquee destination for entertainment, dining, shopping, even residency in a prime location for the region.
With Arco Arena in Natomas, even through all the boom years of the economy as well as the Kings, I still wouldn't consider Natomas a destination by any means. There's certainly been development in the area, but the shopping and dining there is marginal and, in my opinion, hardly notable because the majority of the retail development in the area has been dominated by your typical suburb friendly chains. There is no night life there, no notable shopping, and the home buyer's market in that area has suffered more than most because of its existence as a flood zone.
There is simply no other location (besides maybe Cal Expo, but that's out of the question now) that offers the collective regional group as much potential for growth to be sparked by this arena. You can't forget that it's not just the railyards that stand to benefit from a boom in development, but across the river in West Sacramento, as well. There's a potential between both sides of the river for a major center of commerce, entertainment and tourism, and frankly, anyone trying to move it somewhere else is being incredibly short-sighted. It's the people with that attitude who drove us to this point of desperation in the first place.