One problem faced by file systems utilizing range writes is the loss of exact control over placement of files. However, as most file systems only have approximate placement as their main goal (e.g., allocate a file in the same group as its inode), loss of detailed control is acceptable.
Loss of sequentiality, however, would present a larger problem. For example, if a file system freely writes blocks of a file to non-consecutive disk locations, reading back the file would suffer inordinately poor performance. To avoid this problem, the file system should present the disk with larger writes (which the disk will guarantee are kept together), or restrict ranges of writes to make it quite likely that the file will end up in sequential or near-sequential order on disk.