The incorporation of appliques within a design has always been a great technique for reducing stitch count and embroidery machine run time. However there are times when it is in fashion and others where it popularity wanes a lttle bit. Right now these are quite a few factors that have caused its popularity to soar.
First of all Laser cutters, both independent and beam lasers which work directly on the machine have sped up the process and made it much more automated.
The wide availablity of applique fabrics and cutting services and lower minimums have made apllque easily available to every embroiderer.
The availablily of knowledge of the technique, through magazines, websites and from manufacturers has make the process much less daunting.
There is also the comfort factor. Many customers find appliques designs more comfortable to wear than designs that are solely embroidered.
There is also sophisticated software offerered to automate the digitizing of appliques and to generate cut lines for laser or other cutting machines.
Last, it is in fashion right now so customers are asking for it. So, if you haven't offered applique up to this point now might be the ideal time.