Why are orange diode lasers still not common although orange LEDs have been around for decades?
LEDs and lasers are different types of a devices.  The light emitting medium in a laser has to be capable of population inversion, where more emitters are in the excited state that in the ground state.  This requires complex 3 or 4 level systems with long lifetime intermediate states.  Once the population is inverted you get light amplification through stimulated emission - lasing.  

An LED just has to emit light, so lots of materials that can be used to make good LEDs cannot be used for laser gain media.  I don't know the detailed energy levels of orange LEDs, but probably they are not suitable for laser gain media.  

Edit:  Based on the other comments, it is worth pointing out that good laser gain media are rare.  Most materials, even those that efficiently emit light, cannot efficiently amplify it and so make bad lasers.  Of those that make good lasers, those that can be electrically pumped are even rarer. That is why high power laser diodes are available at just a handful of wavelengths; there happens to be an exceptional material available for that specific photon energy.