No, we don’t recommend it! It’s wasted money (74 euros?) if your country is eligible for a 3 months visitors’ visa.
If I don’t take the student visa, do I need to buy a ticket proving that I will leave Taiwan?
Yes! We know several students who were refused from boarding the plane because they didn’t have a formal proof that they would leave the country within 3 months.
The solution? Buy a cheap ticket to Hong Kong, the Philippines, Japan or South Korea to go on holiday during the school vacations. You’ll have 3 months in Taipei to make friends and to convince them to travel with you. It’s easy! Don’t throw away those 74 beers (did I mean euros? 
)
Note: Plenty of expats use this trick here. Universities will not recommend it because it’s in their interest to cover themselves in case someone doesn’t read the info thoroughly. As public institutions, they will always recommend the safest solution.
Sandrine
I hope that you are fully enjoying your time in Taipei and that these articles help to make your stay unforgettable. If you have friends who are coming to Taipei soon, help them by having a look on our website myroomabroad to help them to find their new home in Taipei. If you want to join us on a trip, have a look at our events page , we're often 50% cheaper than most travel agents in Taiwan :)
When you come back to Taiwan, is there no doubt that you can enter Taiwan for another 90 days without any problem?
If you ALREADY have an airplane ticket proving that you are leaving Taiwan within 90 days, there is no doubt.
Note that without that ticket, you won’t even be able to board the plane to Taiwan.