Firstly, the overuse of the word “terrorist” is very detrimental to the diplomatic front. It only alienates other parties or provides a moral justification to the users that already exists anyway.
Secondly, Hamas is not like al-Qaeda. Al-Qaeda is an organization heavily influenced by individuals from the central Arabian Peninsula so their national character must be examined. People of this region have a Bedouin mentality. They are unbending and extreme in their outlooks, they respond to no authority, and if one battlefield is unfavorable they will simply move to another.
Hamas is a Palestinian organization. Palestinians have historically been farmers and they still have that mentality. Agricultural societies tend to be some of the least warlike. They only go to war under the condition that what a farmer needs is threatened. The three things most significant to an agricultural civilization are the land to grow their crops, the seeds to plant, and a market to sell their goods. In modern terms, this translates to other things but the same principle exists. The blockade prevents the Palestinians from attaining the seeds they need and the markets to access. Periodic Israeli raids also interfere with use of the land. Thus, peace can be achieved merely by lifting the blockade.
Finally, by alienating Hamas, the West alienates the entirety of the Palestinian people. The two major political entities among the Palestinians are Fateh and Hamas. Fateh is widely regarded as being corrupt among the Palestinians. Because of this, Hamas won the election. By alienating the victors of the election, the West sends a message that the Palestinian vote does not matter and this will make the actual voters very angry. If Hamas is destroyed, another organization will fill the void and it will not be Fateh. Rather, it will likely be a radical organization. Some say Hamas is a radical organization. However, like most radical movements that attain power, Hamas has begun to deradicalize.
Finally, and most simply, the West has nothing to lose by talking to Hamas. The worst that can happen is the status quo.
In conclusion, the West should directly negoatiate with Hamas because they are willining to negotiate and their election into power is a reflection of the will of the Palestinian people.
I know these thoughts are a little scattered but I’m tired so, meh.