"Many" players might not bother with solo campaigns, but I certainly do. I don't play multiplayer at all, so any game that doesn't have significant single-player content is an automatic no-buy. It's a shame in this case, because Battlefront sure looked gorgeous while people were trying it out at the midnight launch last night... but I personally cannot justify dropping $60 on a game that offers me so little in terms of my gaming preferences.
Even if a solo campaign loses some luster after the first playthrough, I can still choose to replay it to get more value from the game. For example, I'm replaying the Modern Warfare trilogy now, with the Bioshock trilogy on deck. I've played through these before, but every so often, I feel the urge to go back through them.
A mostly-multiplayer game like Battlefront offers me almost nothing in terms of value, and actually costs me more money (online subscriptions, DLC) to extract any value at all.