All the methods of yoga are useful and can be practiced. As an example, I practice karma-yoga in my day job, where I do the best that I can do, honestly, and don’t worry about the results. Sometimes, there are good results, and sometimes there are not. Similarly, I practice jnana-yoga in teaching people the knowledge from the Vedic texts, and all my writing can be understood as one form of jnana-yoga. Then I practice some asana and pranayama every day to keep the body healthy and relieve the stresses of various activities. And then I practice bhakti-yoga and treat my job, my teaching, and my body as an instrument to serve the Lord. So, everything can be used if one has the proper understanding. The trouble is that people think that jnana-yoga is by itself sufficient or necessary. The answer is that it is neither necessary nor sufficient. Similarly, karma-yoga and jnana-yoga are neither necessary nor sufficient. Ultimately, bhakti-yoga is both necessary and sufficient. But if this principle of necessity and sufficiency is understood, then with that understanding everything can be used to serve the Lord.
The great Acharyas have demonstrated an understanding of Vedic texts, they have written extensive commentaries, and it is recommended that we read them. Similarly, it is important to keep the body and mind healthy. If these two are not sane or healthy, then none of the other processes can work. Similarly, even while performing bhakti-yoga, the results may not come immediately, but we have to be patient and undergo various kinds of tribulations, so karma-yoga is important so that we can keep performing an activity without a desire for results.
Ultimately, rejecting something is rejecting a part of God as being irrelevant and unimportant. That is not the proper understanding. Science, logic, philosophy, art, literature, music, and all other ordinary things can be engaged in the service of Krishna. But the principle is also that the source of everything is more important than those individual things. So, if Sanskrit is used in the service of God, then it is valuable. If it is used merely to make better computers (as many people are doing) then it is as much a waste of time as any other mundane activity. So, if someone is using these things for God’s service, then there is no distinction between sweeping the floor or speaking Sanskrit. But the principle of bhakti-yoga has to be understood properly.
Yes, there are many people who have a selectively biased opinion of what bhakti-yoga means. In my opinion, they have not read the words of Acharyas, and are not following their examples. The principle is not viraga or anuraga. The principle is yukta-vairagya or renunciation by using everything in service of God. If that principle is followed, then by every activity one makes spiritual progress. If that is not followed, then no activity leads to spiritual progress.