On the one hand we have those opposing this saying smiths will be over-whelmed by so much demand for their services; on the other we have the argument that everyone will take up smithing so it will no longer be lucrative. Adam Smith, OTOH, says that supply and demand will find a price equilibrium: cars need oil changes, oil changes cost money and are fairly easy to do; yet not everyone wants to do it themselves.
Smithing has higher barriers to entry than does grease monkeying.
Taxes are a real-world comparison, but the one I would use is software development. IRL, once someone owns PhotoShop, he or she owns PhotoShop. How does Adobe make more money off its product? Well, you can fix bugs or you can enhance features (the latter eventually becoming unneeded bloat).
If it were possible to keep enhancing gear, then PCs would eventually have to dump their old stuff to get the bright, new shiny things. Players wouldn't like that their old stuff had become obsolete, but they would be placated by having new bells and whistles. This would, however, also lead to power creep on the server--an undesirable side effect.
What the maintenance implementation does is mimic Adobe's move to Creative Cloud licensing instead. Do customers like it? No, but it is a model in which Adobe can continue to be profitable.
Likewise, the only crafting I currently think is profitable is for consumables like potions, varnishes, and missiles--which is a shame for the reason I listed above that crafting is one of the strong, unique features of this server. Whereas one can argue religiously about whether realism equals tedium, it seems to me objectively true that static is more tedious than is dynamic. IMO a system in which every character who wants it can have a lifetime best-of-breed suit of armor after about 6 to 8 sewer bounties will be more static than a system in which the character must periodically interact with another character to get said armor fixed.
No one can accurately predict how onerous this will be without knowing its frequency. Currently, one must get new gear (presumably) whenever creating a new character. Would the new system make repair necessary once a year? That hardly seems a hardship. Every day? Does anyone favor that? Going back to the oil change example, if your car needed oil every day, you would get a different car (i.e., use loot-drop armor rather than crafted).
Adjusting the frequency is easy enough rather than acting like this is some kind of binary doomsday button.
Yet another long-desired positive side effect of such a change that might result: moving high-levels out of the Outskirts. Most really good crafters are (I think) high levels. Yet the only viable place to ply their trade is where the new characters are likely to arrive.
If gear needed maintenance, however, then being a crafter elsewhere might be sustainable.
As far as my personal dog in this fight, I really have none. My reasons for supporting it I've already stated above and they have nothing to do with anything likely to benefit my character (other than adding texture to the world he inhabits).