Speaking strictly from personal experience:
I never heard about praying and or speaking in tongues until a year ago. I heard everybody around me praying in distinct languages (some with great vocabularies and others just a few words). It frightened me b/c the Holy Spirit was sooo thick in there it felt like I was going to faint! Later on someone with the gift of diverse tongues spoke a word and I understood it. It sounded like plain English to me! I thought I was nuts!
In October of last year, I was baptized with the Holy Spirit and right away I began to pray in tongues. My best friend did not get her "language" until later in the week but she believed that God would give her the gift of tongues and she received.
4 months later I can interpret tongues and I get word from the Lord through tongues (which are interpreted) in order to edify my church. I pray in tongues everyday after I've prayed everything that I can think of naturally. Praying in tongues is not an excuse to not pray naturally. At first I would repeat the same sounds and words but now it has become a constant flow and I can pray for hours but it took lots of time to build up my vocabulary just like a child learning to talk.
I won't say that a person doesn't have the Holy Spirit if they can't speak in tongues but it is a gift that is available to all believers and I can't imagine why someone wouldn't want it