First off, great post Lemon, I think for the first time in a long time a logical well thought out post has been made, and I agree
There are a few uses of the walls you did not include - writing you name in the sand, trolling enemies by blocking their roads; creating a path to access an area to attack it and then blocking the path as you leave to cover your escape, but in general I think you covered it very well.
We put a fair amount of effort and thought into the walls we had. They were never a substitute for pvp, the best we could ever hope for from them was to (a) alert us to incoming forces and (b) slow those forces down a little to give us time to respond.
For many of the veterans they have a slew of bots ready to go with good fits worked out long in advance, for many of our players they are busy putting some EP into some extension to allow them to fit what it is they are trying to equip, so it can take quite some time to muster a force to defend and the walls allowed us to do that.
Some people suggest using gate scouts instead of walls/probes, and yes we do when we are doing certain operations, but TOG policy is against using trial accounts for anything other than trailing a game, so it comes down to asking someone to cover a certain point for a certain period, rather than just making up another 3 email addresses and turning up the sound on a spare PC. Likewise to those who suggest the Alsbale population is not interested in pvp, we deliberately split TOG into two to allow those who did not want to pvp to live on alpha without feeling obliged to come over and fight, so everyone left in TOG is by definition interested in PvP.
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I personally think that the walls were great, they were easily (but not trivially) counter able, and if people put together a well thought out defensive position the attackers would have to think through their attack and plan a little, as it should be.
The ability to just randomly build walls wherever you wanted (within reason) and also blow them up was a true sandbox feature, a bold move by the devs and really helped revitalise the Beta island population.
The walls-only-around-the-outpost-but-not-too-close-and-also-not-near-any-SAPs are more or less irrelevant and do not bring with them any of the control that the nearly-unlimited walling had, and also remove probes as any kind of early warning system, forcing people to afk at gates or spam trial accounts once again.