The traditional manner of receiving Holy Communion, kneeling and on the tongue, is an ancient custom of the Latin Church, dating back to the first millennium, that is still practised in the Extraordinary Form.
The General Instructions of Ordinary Form Roman Missal (GIRM 160) extend this means of receiving to the Ordinary Form, if the communicant wishes to receive in this way. Although I have not experienced this myself, I have heard of incidents where problems have arisen with some reluctant clergy who seem not to approve of commincants falling to their knees to receive their Redeemer!
Those who oppose Communion on the tongue and kneeling have no reason to object - for the rationale behind the traditional custom is based on sound theology and practical considerations.