Was there once plans to extend TX 24 to the south and west?
https://www.google.com/maps/@33.1312085,-95.9926539,861m/data=!3m1!1e3
Never heard of any future changes or additions to TX 24. The way the interchange looks to me, it's like they did it with the idea of eventually making it a full trumpet or actual T-interchange, but shopped short for the time being to favor south-to-west and north-to-east traffic. IINM, it's supposed to help traffic between DFW and TX A&M-Commerce.
Looking at the map and GSV, I didn't realize they'd truncated TX 50 to Commerce (it previously overlapped TX 24 down to I-30). I guess it was deemed not necessary to have, and it really wasn't.
TX 24 used to continue west to Greenville and then farther west to McKinney, Denton, Decatur, etc. until the portion west of Greenville was renumbered US 380 in the 1970s.
Looks like when the renumbering happened, TX 24 was rerouted down to I-30 (along the existing TX 50?) and the road between Commerce and Greenville was renumbered TX 224.
The section of SH 24 W of Greenville became US 380 in 1971. SH 24 was re-routed to the SH 50 corridor in 1979, and the old SH 24 became SH 224 at that time.
Source: http://www.dot.state.tx.us/tpp/default.aspx (http://www.dot.state.tx.us/tpp/default.aspx)