- You don't get any documentation, whereas with something more official you will have a complete schematic (so you know which support components will be used), pinout, information about power supplies etc.
- You can't rely on being able to buy the same thing again. Even if you find something with the same pinout, small changes to the power supply or usb-serial converter can ruin your day.
- Shipping will probably take a while (or you're buying from a local re-seller, increasing the cost). Your company probably doesn't have a process for buying from aliexpress, but orders from digikey all the time.
- I've not had a problem with development boards, but plenty of cheap electronics in the same category are really badly designed; a random memorable example: https://www.aliexpress.com/item/1005001621800502.html . They have had their issues, but arduino stuff does tend to be well designed, and vendor development boards are usually reliable too.
- Stuff like the feather ecosystem can be genuinely helpful when prototyping if the cost isn't an issue.
I chance the cheap stuff for personal projects, but if work is paying I'd go for something more expensive every time (and probably wouldn't have a choice).