Of course, there is no compulsion on anyone to practice Yoga. Its a matter of personal choice. Even among Hindus there is no compulsion on Yoga. There are other paths open to them such as devotional, ritualistic, philosophical study and so on.
All paths lead to the same goal....we believe.
Sriram, perhaps you need to delve further into the history and nature of Yoga. It is generally practiced by older Hindus (you are not very likely to find yongsters practising it in India) who are looking to prepare themselves for death. It is a means of slowing one's life systems down prior to death. Or, at least, that is what I have ben taught by Hindus over 10 years of living in India and Nepal.
I don't know from where you get your information, Hope. I have been practicing Yoga for more than 30 years living in India and have studied it fairly well.
Yoga was one of the first 'Sramana' practices in India. Enlightenment through mental and physical effort. It was the way of the ascetics and hermits originally. As it became more organised some teachers began to teach it in their ashrams.
But, in ancient times finding teachers was difficult and students had to travel far and wide to find one. Also the conditions for receiving the teaching were very stringent. The student had to show the required inclination. (no mass classes those days). The student had to live in the gurus ashram for 2-3 years and learn the practice one to one. This is why Yoga was not very wide spread in ancient days and only some adepts practiced it.
Some Buddhists considered Yoga and some of the kriyas as self mortification. From this was born the 'middle path'. Most Buddhists therefore shunned Yoga. It was considered an extreme practice.
But once it got formalized, Yoga was taught by many teachers and many young people have been learning it for decades. Today most youngsters in India practice Yoga.
The point about Yoga is that it is not considered as merely a physical exercise. The practice has very significant effect on the mind and emotions. This could make it unsuitable for emotionally unstable persons.....unless practiced under the supervision of an expert.
Most Christians prefer the devotional path (bhakti marga) and the path of service (Karma marga). They don't prefer the Yogic path or the philosophical path. Which is fine. Whatever works for them!
Actually, in the Gita the word 'Yoga' is used as a general path rather than as a specific system of practice. Hence the Gita mentions Bhakti Yoga, Jnana Yoga and Karma Yoga.....as different paths to salvation or freedom (mukti). So...nowadays the word 'Yoga' is used both in its general sense and in its specific sense (which is most often).