Also, you have to take into consideration the marketing. Smarties, Milky Bar (and other typical young kid sweets) are advertised in conjuction with cartoon / characters, played at key times (i.e afternoon slots while the little darlings are getting their TV fix). Yes it has a lot to do with the packaging but not everything. As an example, Star Bars - they are predominantly bought by adults (don't know why, they're horrible) yet their packaging is yellow with stars, big typeface - good kid appeal BUT the main market is adults. Why? They are very raely advertised and certainly without the cutesy kid's appeal.
So maybe that is another consideration for you.