Financially, building a system that can accommodate every device can be costly due to all the equipment needed to run the variety of tests and the additional switching needed to route signals. You may not even use all of the equipment in the station. You may have the best of intentions to someday use the additional equipment, but maybe your plans change and you don’t. Or worse, your device changes significantly requiring additional equipment to be added to the station increasing complexity and you still have unused equipment.
Once you have the universal test station together you may face some other challenges. Even though you are only using a fraction of the test system you will have to spend the time to validate the entire system and all the paths, something that can be very time consuming depending on the number of interfaces and how they need to be tested. Having a singular universal test station can be very expensive when the system goes down for unplanned issues. If and when the system does shutdown due to an issue, you will spend more time getting it back up and running due to the complexity of the system and you may not have another method of testing your product.
If you do end up building a universal test station and find yourself constantly making variants of your station, or not using equipment in the station for most of the test, then it might not be the most effective approach for manufacturing test.
It can be harder to keep a universal test station up to date. You could spend years and thousands of dollars developing your solution only to have it be obsolete once you are complete. Smaller scoped stations are easier to keep current.
A universal test station is kind of like being a jack of all trades but a master of none. It can do a lot of things fairly well, but not as well as a dedicated station for each test type you want to run. It would be like having to cut down a tree, open a can, and slice an apple. You can do all of these with a swiss army knife but having a saw, can opener, and paring knife may be a better solution. For example, you have a device with a LVDT, RVDT, and power output interface. A universal test station is built to test these three interfaces necessitating two pieces of equipment, an active load for the motor output and a power supply and DMM for the LVDT and RVDT. You start testing and realize that the active load and DMM are only used for half of the test. The rest of that time the equipment is sitting idle wasting time and money. The device or station may not allow for the ability to test using both pieces of equipment at the same time and making the station a multiple unit tester increases complexity and cost. Maybe it would have been better to make two stations. One for the LVDT and RVDT testing and one for motor output testing. This way the equipment is being used 100% on both stations while testing two different units, without adding hardware or software complexity. Now it may not always be possible to get 100% usage out of all equipment during test but it should be a goal.