There is no reason your two-channel sound from an HT system should be inferior to any equivalent 2 channel system. There is no fundamental difference at all.
The only problem with HT is that you have five speakers and a sub - six speakers in all - and if you want equivalent high quality sound to a good two speaker system then you must plan to spend THREE times as much for HT. (If a good 2 channel to your ears can be achieved for 10K then you need 30K for just the audio part of your HT in order to achieve the same)
Cost is the big difference but quality can be found in both.
The only problem with HT is that you have five speakers and a sub - six speakers in all - and if you want equivalent high quality sound to a good two speaker system then you must plan to spend THREE times as much for HT. (If a good 2 channel to your ears can be achieved for 10K then you need 30K for just the audio part of your HT in order to achieve the same)
Cost is the big difference but quality can be found in both.