I guess one cannot pick a non-controversial example. I recently had to deal with someone generating XML by string concat and it worked for years until recently

I guess one cannot pick a non-controversial example. I recently had to deal with someone generating XML by string concat and it worked for years until recently. Something with international characters suddenly started causing problems. The solution was simple; I replaced the code with a proper XML library and it just worked. I didn't even bother to figure out what the underlying issue was. Worrying about the bloat is premature optimization. If your process is actually too slow and parsing is the bottleneck then by all means rip out the XML parser library and roll your own.