Regional language is significant in a the concerned region and to persons belonging to a linguistic community. Thus Tamil is significant in Tamilnadu and also among Tamil speaking wherever they are.
Regional language is important and one should know his or her mother tongue. I think this is more because our schools asks the parents to communicate with their children in Hindi or English. Basically, significance of regional languages lies in the fact that it helps us to remain attached to our roots. I live in a Bengali speaking region and I love Bengali speaking and since my mother tongue is Hindi, I learnt a lot about Hindi literature but at the same time I have great love and respect for other languages too like Gujrati, Malayalam and Punjabi.
Speaking our regional languages saves it from extinction and people can share about their own languages and cultures with others which is the beauty of regional languages. We cannot imagine a world where only one language is spoken and hence I feel the importance of regional language is great in our life or global life...