Okay, I'll give my comments as Division Captain here.
Firstly, I am quite happy to discuss matters like this is the forum, as long as there is no finger pointing (ie. claiming a specific player cheats) and it remains cordial. Where possible the community helps define the rules based on how they like to play the game. That said, once discussed, I don't want old arguments to resurface without new context. In this case, it is a new argument and FTB is a new context.
Secondly, the Feed The Beast is still a trial in many ways. Part of this trial is working out how people play it and what rules we need for it. So far, we have removed at least one mod because it seemed to be stopping the server working. That may be returned in the future. Some players play FTB without machines. Some use them large scale. The Admin team has to consider all of that when working out what is best for the division in any changes we make. With so many mods in the FTB, it being "Beta" and so many different mod additions to vanilla Minecraft, it is hard to get any balance for every type of play.
Thirdly, the rubber boots do seem to be a bug but they do have a purpose still in the game. From the wiki it seems that it is mainly to minimise fall damage for IndustrialCraft2. As has been discussed, a question is whether such benefit can be gained from any other item for such a low cost (ie. a recipe that just requires naturally found substances, both of which are obtained using a simply crafted tool). As to whether it should be regarded as an exploit, does anyone know what the mod developer is planning to do/has done about it? We have banned sand creation exploits in the past because we knew Mojang were going to fix them and that is vanilla Minecraft. This is a feature added by a mod pack. Therefore, it is harder to regard as an exploit due to its nature.
Fourthly, the Admin team has various tricks up our sleeves in order to do our job, but we don't want to have look over every player's shoulder. We do care about whether players are enjoying our servers, but until we see blatant cheating or actions hurting the server or the community, we are not planning to set rules. As the rubber boots is an issue under discussion that has only come to light in the last week, we haven't rushed to judgement.
Hope this helps everyone understand better the background from the Admin point-of-view.