First, there are a lot of questions about how both TOEIC and ETS are run. But let's ignore those for now. The real issue is whether or not TOEIC proves a very good match for university students. Is it a good English proficiency test? Problems with TOEIC include:
1. It's too long. It's easy to get behind the audio during the listening test, and it's hard to concentrate and keep on pace to finish the reading test. About 3 hours are required to take the test, much of it concentrating intensively on the test problems.
2. It lacks practical communicative tasks--especially ones that require any real production, such as speaking or writing.
3. Its main focus is business and business traveler English, so it is schematically outside of the experiences and immediate needs and interests of university students in Japan.
4. It too much an EFL literacy test: half the test is 'reading', and the other half, the 'listening' parts, require reading as well (e.g., Parts 3 and 4).
5. It's a norm-referenced test that basically puts inexperienced 18-22 year olds in direct competition with older, more experienced company and government workers for their 'level of attainment' in the tested group.
6. It's hard to analyze students' scores in order to come up with a better study plan for them. Many Japanese students think that their reading skills far exceed their listening ones. But at the lower proficiency levels (the bulk of the students here), the more typical pattern is for them to do much better on the listening sections of the test than the reading ones. However, it is difficult to devise a better study plan for them. It seems, though, for example, lower level learners might more quickly boost their scores by concentrating on the parts that they can master more quickly--which are probably Listening Part 3 and Reading Part 5.
7. Studying old tests and pseudo-TOEIC questions might help produce test-wiseness in the students, but these prove time and again to be horrible ways to help students learn English. What is needed is better-thought-out exercises and activities that help students learn, revise, and review the typical English that they need to take the TOEIC. The main thing taking practice tests does is reinforce failure and under-achievement.
Perhaps these issues also hold in places like China and South Korea too, so it is little wonder then that governments and institutions in Asia are seeking to develop language proficiency tests that might fit national cultures better. It is also understandable why some might want to develop a better language proficiency test for young adults, such as university students typically aged 18-22.