Withers in faction bases

Since 1.4, people have been using withers as the ultimate griefing machine. Especially in my factions world, players create them by enemy faction bases. Is this cheap? The players have a blast, but if you got griefed without loosing power, it's kind of cheap. A couple of my mods think we should remove it, but I would like some opinions from other server owners

 

I dunno how cheap that is. You have to grind a ton of wither skeletons to get enough heads for one wither. If they are going out and farming skels for the hours necessary and then using em in a war id say that they are just prepared. Now if they can magic up the skulls in little to no time then Id be looking to adjust that but on my server we farmed up enough skulls for 4 summons, it took about a week of off and on farming.