To the best of my knowledge (please contribute if I'm mistaken) the MIDI connector has never been available with an integrated locking mechanism found on professional quality XLR connectors. The MIDI specification was defined by the MIDI Manufacturers Association (www.midi.org). Perhaps this question should be addressed directly to them. Not every manufacturer integrates a cable hook into the design of their equipment, including almost all premium quality analog devices and many top-of-the-line keyboards with MIDI and MIDI keyboard controllers.
If MIDI is working and you've restrained the cable with velcro or a cable tie then you are employing best professional practices successfully.
best regards,
Blair Francey
Fireface 802/ARC USB; HDSP Multiface x 2; 2023 AMD Windows 10 Custom PC