It's true that the northern hemisphere had the majority important telescopes... several decades ago. Actually, interest in installing telescopes to study the southern sky began as early as 1820, when Great Britain founded the Royal Observatory at the Cape of Good Hope, the first scientific institution in Africa. Following a few mergers and changes, the South African Astronomical Observatory was established in 1972, now operating one of the largest telescopes in the world - a 9.2 meter reflector telescope, the SALT, completed in 2005. In 1972 Another major southern telescope was built in 1974, in Australia, at the Siding Spring Observatory, housing the AAT, a 3.9 meter telescope.
The first modern large-scale reflector telescopes, that used photographic plates and films, were built at the beginning of the 20th century. The first telescopes having the primary mirror with a diameter larger than 1 meter were the Hale telescope (1908) and the Hooker telescope (1917), at Mount Wilson Observatory. After the vacuum evaporation coating technique was developed at CalTech, larger primary mirror diameters were possible, and for many years the 1948-built Hale reflector telescope at Mount Palomar was the largest telescope in the world having 510 cm primary mirror diameter. So far, most of the large telescopes were in the northern hemisphere.
In 1953, a shared European Observatory is discussed for the first time, and one year later it was established that this observatory will be placed in the southern hemisphere. The ESO charter is signed (ESO is celebrating 50 years these days, btw), and in 1966 the first telescope used in Chile received its first light. Right now, ESO is operaing one of the most advanced optical instruments, the VLT, which is actually an interferometer using four 8.2 meter main telescopes and four 1.8 meter auxiliary telescopes. Plans are under way to building the EELT, a 39 meter main mirror optical/near-infrared telescope, which will be the largest telescope on Earth by the time of its completion.
In conclusion, we have lots of world-leading telescopes in the southern hemisphere that hunt for planets using multiple techniques, including Doppler-shift spectroscopy, transit and direct imaging.