Standard base tiles cannot be upgraded to Plastic Tiles like other types.

It's not a good idea to do that anyway. Overbuilding a tile with a tile of another material will destroy the material used to build the original tile.

Similarly when replacing a pipe with insulated pipe or vice versa, original materials are lost again.

In the lategame u have 100 tons of the most materials. Who cares about a couple of lost materials ? Better fast replacement than stupidly deconstruct and build again. Have u ever run out of raw materials ? Except Sandstone, Obsidian, Abyssalite. I don't think so.

Good, bad, or otherwise. I don't care if they all allow, or all don't allow, but it is a matter of consistency for them all.