Look at 4X bikes. Some are very short in the top tube but not all – slack, strong, short travel.
Nicolai developed the Helius TB as a shorter travel trail bike – c120mm front or rear (you can run a little more or less). Looks like it would be ideal for trail centre riding. Not selling at all though – the interest is all at the 140mm level or above and has been for some years now.
As others have pointed out, you don’t save a lot of weight reducing the travel on the frame – most of the weight saving comes from lighter parts. 150mm forks etc got lighter. An air shock weighs the same on a 100mm bike or a 150mm bike at 200mm eye to eye (which will cope with both).