There is a parameter for altitude, just like for heading. The format is alt:xxxx
Example: {{Location|42|15.75|0|N|42|39.56|0|E|alt:153_source:exif_heading:122.141343}}
The GPS-attitude from cameras has such an high noise level and is in some cases completely wrong so that it's IMO not useful. This is also the
If we completely ignore altitude data then we just discourage users that do provide the data. It might be worthwhile to compile a statistics of altitude values (which percentage does provide them, histogram of values etc.)
I have been running a bot that extracts GPS EXIF data from files and adds the Location templates, so I would have access to such data. Looks like that bot can be retired once everybody uses the new upload wizzard.
For me more important is the heading parameter, we have an usage of that on para's map
and the Wikiminiatlas of course