Humans are one of the species which are attracted towards colors and pleasant smells. This thing led many scientific discoveries, as the humans first pondered on the blue sky, the yellowish and redish fire etc which led further some important discoveries. 

What I am trying to tell is that

                                                        Due to a natural tendency of attraction towards the colors and pleasant smells, humans are attracted towards flowers.

This was discussed at length in the question 'Why do plants smell better than animals?', which can be found in the Plant section

It could be a coincidental result of the fact that primates have unusually good colour vision, or a side effect of having evolved from animals which displayed rainbow-coloured patches to indicate sexual availability.  But it's also true tjhat many flowers are edible, and they tend to come out in spring when there isn't much else available.

European hedgehogs often anoint themselves with strong-smelling substances, chewing them up and then spreading the scented sailiva over their backs.  This presumably has a practical purpose - probably to disguise their scent from both predators and prey.  But I have found that they seem to derive pleasure from shoving their faces into strong-smelling herbs and snorting about in them, even if they aren't going to use them to self-anoint with.

My hypothesis (I don't know if this is new to science): We evolved fromf fruit eating monkeys. The flowers we find pleasant developed as a mimikry of monkey-targeted fruits targeted at insecs eating such fruits.

Fruit-eating Primates co-evolved with fruit trees and developed colour vision to be able to spot ripe fruits over distances. The result of this co-evolution was colurfull sweet fruits with aromas pleasant for those primates.

In a second step, some insect species, like some butterflies and  wasps or wasp-like insects, started using such fruits as a source of food. They developed the ability to spot their colours and aromas.

This provided an oportunity for flowers to be polinated by such insects by immitating such fruits. The results where flowers that looked like fruits for those fruit-eating insects: for the visual system of the insects, they resembled such fruits in shape and colour and had scents similar to those of monkey-adapted fruits (perhaps from classes of chemicals similar to those appearing in the fruits) and provided sweet, sugarry sap (nectar). As a result, these flowers generally looked and smelled atractive for fruit eating primates too.

Plenty of mammals are pollinators that eat flowers, their pollen or nectar, including many “possums”, bats, monkeys, mice etc. Some flower species have adapted  to such creatures, for instance, several Proteas actually grow their colourless or brown flowers  face down practically on the ground. They are scented, but smell of mice! In season you may see our field mice with pollen-gilded faces. Some bird-pollinated flowers are practically scentless, but conspicuous. Bat-pollinated flowers often are scented only at night, and some, such as baobabs, are adapted to be eaten after being pollinated by fruit bats, leaving only the fruit rudiment.

As for humans, fruit and even some flowers have played an important role in our diet for longer than the evolutionary history of the anthropoids. Scents of flowers tend to be fruity, and their colours often are conspicuous and associated with plants that promise treats, including edible visiting insects, and intriguing appearance. To enjoy and seek out such objects would be a survival factor. As our investigative and flexible intelligence developed, bright colours, vivid scents, and striking shapes began to attract us more systematically than most other animals, and down the ages the trend has intensified rather than slackened.