Maybe that'll change with starter deck 14, but it's doubtful
Sunscape Familiar Combo players love Sunscape Familiar due to its ability to reduce mana costs, making it easier to set up explosive turns or synergies with the likes of Snap to gain access to more mana in turn
I've played Hymn to Tourach in Legacy BUG Delver, and it has even seen play in Vintage Dark Times before
Mishra's Factory is still a fine card and has plenty of application but it is far from an auto include in aggro lists, even mono coloured ones (apart from the fact there are often other better colourless lands options on offer)
And after Khans of Tarkir was out, Dig Through Time was added to the mix, and it just felt like an absurdly good deck to be playing
Multiple copies of this card on board will deck your opponent very fast with many cheap, instant speed crimes such as Take the Fall