TextMate was suffering from not being open sourced, and hadn't shown any improvement in 7 years. So he open sourced it, and it is now actively developed by the community.
TextMate was suffering from a lack of development. Someone else took over development, in this case the community.
Had TM continued in its previous, active commercial mode, it may be ever more popular today, not having given alternatives a chance to in turn become popular.
