why is 61409 marked "obsolete" ??

[Chris Böhnke]

i think partly because this part is named "~Slope Brick 18  2 x  1 x  0.667 Grille (Obsolete)"
should obsolete parts also include which part replaces it (like moved-to)?
sometimes there are also 2 or more successor parts (big rework with more details and variants came later)

I like that idea.