The aim was to unite all the people of India by one single thread of devotion.
Different people in India speak different languages. In Kashi (now Varanasi) there is a different language, in Rameshwaram there is a different language.
In ancient times, people were told to visit Rameshwaram, and then from there they were told to go on a pilgrimage to Kashi and bathe in the holy Ganges. After that they were told to bring back with them the holy water of the Ganges from Kashi to Rameshwaram and offer it to the Jyotirlingam there. And after that, they were told to take the offering back to the Kashi Vishwanath temple.
The intention behind doing this in the olden times was to bring a sense of national unity (by visiting these holy shrines situated in different parts of the country).
It is not that Lord Shiva requires your offering of holy water. What would Lord Shiva do with it? All the water in creation belongs to Him.
Taking holy water of the Ganges from Kashi to Rameshwaram has no meaning or importance to Lord Shiva. Yes, but there is a certain significance in it for the country.
When people undertake pilgrimages together to different parts to the country, they establish bonds of friendship with one another.
See, people from South India go on a pilgrimage to the Amarnath Shrine in North India. So this pilgrimage becomes a medium to connect and unite the people from Kanyakumari in the south with the people from Kashmir in the North. The pilgrimages become a medium to do this.
And whenever we do anything with a sense of sacredness and purity, our entire consciousness starts blossoming. That is why all the twelve Jyotirlingas were never kept in one place or one state. Some were in the north, some in the south, some in the west – they were distributed all over.
And in those days, all those places were very difficult places to travel to. It used to be so difficult to reach there. One had to go through dense forests, dangerous valleys, city ruins; or on the top of high snow capped mountains, etc., to reach the shrines.
For example, Kedarnath shrine is situated deep in the Himalayan range.
In this way, by establishing Lord Shiva through His sacred shrines in different parts of the country, the holy sages and saints of those days built a unified nation.
Also, it is said, ‘Tatropajagmur bhuvanam punana mahanubhava munayah sa-sisyah prayena tirthabhigamapadesaih svayam hi tirthani punanti santah’
- Shrimad Bhagavatam (Canto 1, Chapter 19, Verse 8)
This means that wherever a holy saint sits, that place itself becomes a holy place of pilgrimage. So many saints have visited these holy places, meditated there and have done Tapasya (penances), and that is how the sanctity and glory of these places has grown over time.
However, today you find that these places are unclean and mismanaged.
Nowadays, so much milk and other offerings are offered carelessly in a wasteful manner at these places, without the sense of devotion or faith. They just rush you through the rituals and the oblations. This is not Pooja. Worship which is done mindfully, with a sense of devotion and in a meditative state becomes Pooja in the true sense.
If you just do Pooja to fulfil your own selfish desire or appetite, or to fulfil some monetary obligation, then you are only fooling yourself. So one should not do that, you should do it with a feeling of devotion.
When the Rudram (a series of verses recited in praise of Lord Shiva) is being chanted and the Shivalingam is being bathed with water, we should simply close our eyes and sink within, into our own Self. We should go deep into meditation. Then that is meaningful.
We should experience that eternal vastness of the Shiva Tattva (Tattva means principle or element) which is manifest everywhere as the blissful Chidakasha (the Space of Supreme Consciousness).