Not necessarily. A towel with a higher GSM will feel rich and luxurious and is a wonderful treat to wrap yourself up into after a bath. But the extra density in the towel adds weight and thickness and means it's slower to dry, because of the additional fibres in the fabric. Lighter GSM towels are great for packing in your bag for holidays, swimming lessons or visits to the gym as they pack down into a smaller space, feel lighter and dry more quickly.
If you have a busy family bathroom or a lack of hanging space for towels, you might prefer the faster-drying virtues of a lower GSM towel.