By old Mission, do you mean back when the forms of energy were separated into 5 categories (mechanical, EM, electrical, etc) and you get 10 points each time you use a different type of energy (up to like 3 of times)? If so, the problem with that is people would find the most reliable form of each of the different types of energy and put them into a module then replicate that module. This was a really effective way to do build their Mission because they have a total of 5 different energy transfer (plus the starting and ending tasks) in their entire Mission. They then have a number of these identical modules as spares that they can just interchange if they wanted to. While it may seem open ended in reality, people were just using the same thing over and over.
Also, these tremendously open-ended events led to a huge number of clarifications, arbitrations and safety issues (in addition to scaring off new teams who have no idea where to start). While I enjoyed the old mission rules, I kind of shudder to think about some of the things we were doing to both build and run those devices.
Finally, I simply fail to see how requiring a ramp is qualitatively any different from requiring a gravity powered launcher, self-contained gravity powered launcher, non-metallic elastic, electric motor or mousetrap propulsion. While it is conceptually more simple, restrictions on energy have always been a part of the vehicle events, it's just a different variable you have to optimize every year.