Walls as they are now will slowly destroy roaming pvp as islands get more and more spammed.  Some alliances have cut off strategic paths others have simply spammed the entire island leaving a narrow path to walk through.

Whatever the thought processes behind it, it will make roaming a boring clear a path affair, get bored, go home. 

Since there is no limitation once again on who can spam walls and you can effectively build them quicker than you can destroy them without bombs and it takes about 3 bombs to take out a fully grown wall.

I like the idea of giving some defences to the proximity probes etc but i think they need to be linked to something that generates power on them like the probes, tp's or outposts.

Lets face it if someone was really bored they could wall your entire island

Just my 2 cents worth

And yes its affecting my ninja mission running as well