At the height of the current conflict in Iraq, US troops totaled around 150,000 with at least 100,000 private security contractors, for a total of 250,000 US personnel. Add that to non-US coalition members, who all together numbered around 50,000.* 300,000 was the largest number of people the MNF could commit to Iraq, even though in 1990 the US was able to amass more than twice as many American soldiers and many more Arab members of the coalition.
Yes I do believe the overthrow of Saddam's murderous regime and democracy in Iraq would have been much easier to achieve in 1991, given what had already happened by March of that terrible year, and considering the consequences of allowing Saddam to maintain power after 1991.
*Numbers are approximate.
PS: There was no Al Qaeda in 1991. In 1990 "Bin Laden offered the services of his mujahedeen to King Fahd to protect Saudi Arabia from the Iraqi army."
In 1990, "The United States assembled a coalition of forces to join it in opposing Iraq's aggression, consisting of forces from 34 countries: Argentina, Australia, Bahrain, Bangladesh, Belgium, Canada, Denmark, Egypt, France, Greece, Italy, Kuwait, Morocco, The Netherlands, New Zealand, Niger, Norway, Oman, Pakistan, Philippines, Portugal, Qatar, South Korea, Saudi Arabia, Senegal, Sierra Leone, Singapore, Spain, Syria, the United Arab Emirates, the United Kingdom and the United States itself.
Although they did not contribute any forces, Japan and Germany made financial contributions totaling $10 billion and $6.6 billion respectively. US troops represented 73% of the coalition’s 956,600 troops in Iraq.
Many of the coalition forces were reluctant to join. Some felt that the war was an internal Arab affair, or did not want to increase US influence in the Middle East. In the end, however, many nations were persuaded by Iraq’s belligerence towards other Arab states, offers of economic aid or debt forgiveness, and threats to withhold aid."