I just bumped into this question in which the doubt has emerged right after a conversion process. More often than not people who are willing to answer does not have time to go through the whole process to reproduce cases like this. Wouldn't it be helpful to have the hability to attach the .ai or the .svg directly into the question to allow their manipulation to find a quick answer?
This is an issue that has been addressed in the past, both on this Stack as on the whole network. There are three main arguments against enabling file sharing:
Security. After all is said and done, most users on SE are complete strangers to each other. It is pretty trivial to disguise a virus as an svg file, or even inject a legitimate .ai file with malicious code. It is not smart to just download and run any file some stranger shares with you online.
Hosting cost. Truth is that the Stack Exchange Network is huge, and already takes a lot of server space. Server space costs money, which is problematic for a service which is (mostly) free. Now imagine if they would also have to host 2GB .psd files and badly compressed PDF files. Additionally, they would also have to implement a virus scan for these files and extra security checks on all these uploads. This is also why images are hosted by imgur for example, since they already have all these security measures and the hosting space.
Already exists. There are plenty of services online that can host and share files, from Dropbox to nofile.io. If you really want to, you can already share a file pretty easily.
Besides the excellent points that PieBie mentions in his answer, there is the fundamental reason that this doesn't fit the Stack Exchange format. I'll elaborate.
Most often, a question that requires sharing a file by the Asker, is off-topic. Either it is a hidden request to do free work ('please fix this stuff in my file for me'); or it exactly matches our first Off-topic close reason:
Solving this problem requires access to a specific setup, file, or interaction with you or your machine. Questions on this site should be potentially useful to future visitors, not depend on external resources, and be answerable without trial and error.
Allowing attachment of (non-image) files directly in the Question would encourage more of these unwanted off-topic questions.
Lastly, the lasting value of such a Q&A exchange to later visitors would depend on access to the file(s) in question. As PieBie notes, keeping all these files around would be very bothersome and expensive.
A common misconception is that Stack Exchange is a forum, where you can post any question and any discussion. This is simply not true, as both the tour and our on-topic definition can attest. Please remember that Questions ans Answers must be valuable to later visitors who might have similar problems. This deliberately excludes troubleshooting questions.