There were several options for the Allied attack :
- force the harbour and destroy the eight French galleys (suicidal).
- land the army under the cover of a bombardment by the fleet on the isthmus dividing Cádiz from the mainland (a leeshore).
- bombard the city and ask it to surrender (hearts and minds).
- land the Allied troops between Rota and Cadîz.
They chose the last option, a landing far away from Cadîz and without any real way to harbor the fleet or to immediately eliminate the threats of the forts protecting the harbor and the city of Cadîz. Winning hearts and minds won't give you the control of the two forts on the Portales (St Lawrence, St Matagorda). It also won't give you access to Cadîz Bay and to the inner harbour.
- Without access to Cadìz Bay, your ships will stay anchored off a leeshore, which is dangerous in bad weather and not really good for morale.
- Without control of the inner harbour, you won't be able to destroy the Franco-spanish galleys lurking off the harbor and harassing your own ships.
You also need to be careful about the Spanish land troops, Villadarias was able to recapture Rota, close to the allied landing zone and blocked a possible access to the Bay of the Bulls, the last place to harbor the ships in case of bad weather.
The Anglo-Dutch forces left after the recapture of Rota and because they were unable to take the fort of St Matagorda. Without the looting, they would perhaps have gained a day of action, but I don't think it would have given them Cadìz. They already waited two days on the ships before the landing ...